30: faster in-game downloading - jitspoe, Smokey, Tinman, Gremlin, P!nk, eiii, atte, b00nlander, SkateR, Playah, ViciouZ, nightryder, oli887, toM|vendettA, Gold_Leader, l1g, Clipz, Sharp, Waggot, Zorchenhimer, basilo, Sandwraith, kNoC, y00tz, Nitroboy, Termin8oR, nofearvladi, Krizdo4, Warlord
15: More high-res textures - Gremlin, bitmate, b00nlander, SkateR, oli887, Gold_Leader, l1g, TinMan, MosheD, Spook, Sandwraith, spacepirate, Nitroboy, kNoC, nofearvladi, Warlord
13: Vwep (see what weapons people are carrying) - bitmate, KnacK, XtremeBain, SmackWaters, SkateR, ViciouZ, toM|vendettA, Gold_Leader, Waggot, basilo, eiii, Nitroboy, Warlord
9: Increase paintball visibility - S8NSSON, PiCaSSo, oli887, Dirty_Taco, nightryder, Playah, Spook, Gold_Leader, Nitroboy
8: New map format - P!nk, eiii, bitmate, b00nlander, Cobo, ViciouZ, Zorchenhimer, {appy Hamper
8: (Option to) disable colored text in chat - Anarchy, SkateR, Clipz, Waggot, basilo, KiLo, Spook, TinMan
7: Central server for mapinfo files - jitspoe, DirtyTaco, T3RR0R15T, eiii, TinMan, nightryder, KiLo
7: (Option to) disable funnames - Spook, eiii, TinMan, Clipz, basilo, KiLo, Termin8oR
7: Leaning - magalhaes, atte, bitmate, ViciouZ, Sandwraith, kNoC, Nitroboy
7: New gun models (such as the Angel) - Gremlin, iEATnoobs, l1g, Clipz, Sandwraith, Nitroboy, Termin8oR
7: Client-side demo auto-recording - Zorchenhimer, XtremeBain, magalhaes, Spook, {appy Hamper, TinMan, atmays
5: Don't require mouse to be over edit fields to type - oli887, jitspoe, Sharp, basilo, T3RR0R15T
5: Client-side auto end-game scoreboard screenshot - XtremeBain, Spook, {appy Hamper, TinMan, SuperMAn
4: Kill cam (like in CoD) - nightryder, toM|vendettA, l1g, enozpp57
4: Female player model - T3RR0R15T, SmackWaters, Spook, magalhaes
4: Screenshot system for cheat detection - ch40s, Clipz, Sharp, SuperMAn
4: Vote kick - SmackWaters, nightryder, Sharp, Sandwraith
4: Better bot AI - P!nk, jitspoe, ViciouZ, QueeNiE
4: Global-login based bans - XtremeBain, KiLo, T3RR0R15T, SuperMAn
4: Save console command history to a file so when you load the game up again, you can hit the up arrow to get the last typed command. - jitspoe, T3RR0R15T, TinMan, Cobo
4: In-game voice communication (VoIP) - SkateR, Clipz, ch40s, Termin8oR
4: Ability to use embedded quotes (so people can have spaces in their names when set from the menu) - jitspoe, T3RR0R15T, {appy Hamper, Shadow
4: Wall jumping - SkateR, Dirty_Taco, Sandwraith, ch40s
3: Global-login based logins (ops) - XtremeBain, jitspoe, T3RR0R15T
3: PK3's - Smokey, b00nlander, TinMan
3: Dashing - SkateR, Dirty_Taco, magalhaes
3: Map-specific chat logging (so we can get player feedback on the maps on the beta server). - jitspoe, magalhaes, ViciouZ
3: Round countdown timer for siege maps. - KnacK, magalhaes, Zorchenhimer
3: Wave animations - T3RR0R15T, Zorchenhimer, TinMan
3: New sounds - iEATnoobs, nightryder, TinMan
3: Variables in menu widgets (for map preview screenshots) - Zorchenhimer, l1g, {appy Hamper
3: Option to set crosshair size - jitspoe, Spook, TinMan
3: Team autobalance - ch40s, TinMan, magalhaes
3: Mouse fix for vista - digi, SkateR, y00tz
3: Sort buttons on (in-game) server list - oli887, TinMan, SuperMAn
3: Support for left and right mouse wheel. - KnacK, Spook, Nitroboy
3: Indicator for password-protected servers - abrken, magalhaes, nofearvladi
3: If the server has a fatal error, try to load a map rather than leave the server down. - jitspoe, KiLo, kNoC
3: User option when to respawn when the mandatory respawn period is reached. - KnacK Zorchenhimer, y00tz
3: Tie global login accounts to forum accounts - y00tz, KiLo, kNoC
3: Warmup mode before match starts / while waiting for players - jitspoe, bitmate, Apocalypse
2: New (selectable) player skins - bitmate, iEATnoobs
2: New menu format - Cobo
2: Grapple - loial21, ch40s
2: Sharp turns -SkateR, Dirty_Taco
2: Map pack. - oli887, Gold_Leader
2: Work on the player models - Clipz, Sharp
2: Weapon and item autoswitching - jitspoe, oli887
2: Customizable word filter - {appy Hamper, jitspoe
2: Allow angles to be used for func_rotating so s8n can finish his catapult map. - jitspoe, ViciouZ
2: Global-login STDLogs logging - XtremeBain, T3RR0R15T
2: Map notifications for standalone serverbrowser - jitspoe, T3RR0R15T
2: Ability to add clan tags to player models - Clipz, T3RR0R15T
2: Scroll bar in the console - oli887, T3RR0R15T
2: Optimize file checking to reduce load times and game hiccups/freezing - jitspoe, T3RR0R15T
2: Don't try to download textures if an rscript exists for that texture name. - jitspoe, T3RR0R15T
2: Download textures required by rscripts. - jitspoe, T3RR0R15T
2: Places to enter IP and password in the join game menu. - nightryder, Spook
2: Standardized matching rules - iEATnoobs, magalhaes
2: Server list filters - Anarchy, TinMan
2: Get rid of player model in first-person chase cam view. - nightryder, TinMan
2: Ability to choose the other team's color - Clipz, TinMan
2: Use libcURL for people having issues downloading the serverlist and connecting to the login server - jitspoe, TinMan - using UDP instead
2: Option to set crosshair color - PiCaSSo, TinMan
2: Flashing flags on HUD - kNoC, TinMan
2: Cvar that stores the map name - KnacK, TinMan
2: Ability to select and copy text. - kNoC, TinMan
2: Make the loc file system use the closest visible loc, not just the closest - b00nlander, jitspoe
2: Display topspeed on the scoreboard. - lekky, Termin8oR
2: Melee attack (barrel tag? paintbrush?) - enozpp57, TinMan
1: Bombing run game mode - T3RR0R15T
1: Menu links to download more maps - Gremlin
1: More cheat detection - Gremlin
1: Ugly Q3 name colors - TinMan
1: In-game clock (with alarm) - abrken
1: Enlarge lists (server lists, scoreboard, etc.) to display more characters - abrken
1: "Best of" page to display the most popular maps / best players - abrken
1: 2-layer textures (might require a new map format) - S8NSSON
1: Random texture selection - S8NSSON
1: Context dropdowns in scoreboard for ignoring, etc. - Playah
1: In-game chat (Connect to IRC server, perhaps?) - oli887
1: Allow all maps supporting 1-flag mode to be playable in PONG mode - jitspoe
1: Alphabetize map and demo names - nightryder
1: Setting to chasecam just enemy players - iEATnoobs
1: Add a column to the scoreboard that calculates skill or performance - Uncle
1: Option to disable "blocking" for jump maps - Clipz
1: Optimize water code for better framerates - Sharp
1: Change the main menu screen - Sharp
1: More DSM options for entities (so I can finish pbcup/arctic_dsm) - jitspoe
1: Option to set text color - PiCaSSo
1: Tie the wiki into the global login system to prevent abuse / spambots. - jitspoe
1: Add support for bulleted lists to the wiki. - jitspoe
1: Add image uploading functionality to the wiki. - jitspoe
1: Fix bug on wiki where 3rd level header sometimes gets merged in with the text instead of being put on a new line. - jitspoe
1: Laser entities - Clipz
1: Don't load all rscripts for every map -- just the ones that are applicable. - jitspoe
1: Akimbo (dual wield) feature - {appy Hamper
1: 64bit Linux support - Phenax
1: Client-side setting for "id" - basilo
1: Somehow make the loading image compatible with non-US keyboards. - basilo
1: Allow loading/saving configs anywhere on the filesystem. - basilo
1: Support for regular expressions in menus. - Zorchenhimer
1: Get rid of the old-style scoreboard at the end of the game - XtremeBain
1: Add a button in the bind menu for fastforwarding demos? - Playah
1: .skm shadows (used on the new player model) - kNoC
1: Self-reflection in the water - kNoC
1: Password reset option for global logins - jitspoe
1: Central repository for textures and other content - kNoC
1: Hardware bans - Anarchy
1: Increase limit for loc files - b00nlander
1: If the number of entities exceeds the maximum allowable, start removing paintballs instead of causing a fatal error. - jitspoe
1: Make the server not hog all the CPU if there is a fatal error. - jitspoe
1: Ability to customize player appearance (different jerseys, pants, etc.). - Nitroboy
1: A mod install pack with gui interface that includes a comprehensive user guide with demonstrations of all tweaks. - loial21
1: Ogg vorbis support - TinMan
1: PNG support - jitspoe
1: Include Zorch's menus - kNoC
1: New player models - Termin8oR
1: MVP on scoreboard - Termin8oR
1: Ability to communicate with http/mysql through menus (?) - Shadow
1: Aliases with parameters - Shadow
1: Grass flag for textures that renders 3D grass - Cobo
1: Round time limit (for CTF, elim, etc.) - KnacK
1: Improved 3D audio support (OpenAL) - P!nk
1: Display map name and game mode at the beginning of the match - Zorchenhimer
1: Better menus built-in - Krizdo4
1: Free for all game mode where a player gets points for holding a flag - Apocalypse
1: Display the kill count of the highest player in DM mode on the HUD - basilo
1: Don't count down the timer in DM mode when there are no players - jitspoe
1: Double sided paint splats (so they show up on windows) - Krizdo4
1: Change the default gaming screen resolution - bitmate
Cobo: It handles mods in the same way quake2 does. You should be able to run most Quake2 mods on it. I have concerns about people making server side cheats, though, so I don't have the mod source available. It also seems kind of weird to have mods for a mod. And people's mods would constantly have to be updated/rewritten/recompiled when new versions of the official game are released (and more than likely, they wouldn't be, leaving old server versions running with potential exploits, etc. since they don't patch). Also, there's already starting to be a lot of debate about some of the basic settings, such as elimination time. Having various server mods that change the gameplay could further split the community.
Warlord: As mentioned, pak files are already supported. I personally think it's simpler to just have the files loose. It's easier to update specific files and you don't have to worry about clones/different versions of the files floating around in the same directory that are stored in paks. Naturally, several maps are packaged and distributed in zip files when they include custom textures. These can simply be extracted to the paintball2 directory.