Here's one of my twice a year posts:
-Maybe set a time each week when people should try to play. Let's say from 6-9pm est, or whatever time really. It at least would help to gather a few more people online. I stopped playing because of the lack of people on at a given time. I think if you knew people were going to be on, you'd be much more likely to log in for once. Even if it starts as a weekly event, it might drag people back into the game.
-I realize one of the coolest features about this game in its hayday was to be able to create your own server, and let people join up, but I think in the long run this hurts things. Typically, if I start the game up, there's about 3 servers with maybe 15-20 people total, and then about 30 empty servers. If there were a limited number of servers, preferably ran by people who knew what they were doing, and had a decent map list going, it would be help to not spread the population out so much.
-Limiting the number of maps available. Even if the list is narrowed down to around 50-100 maps, it would still be better than the 10000000 we have now. If the two ideas were combined, have a few servers running a few different styles of maps. Siege, DM, TDM, etc. And try to make each server dedicated to only playing maps that are similar. GO ahead and have some pubnoob maps like wob, ubcliff, etc, but then have most of the servers running some nice maps that the community likes.
Also, unbans. Send out an email to the folks, welcome them back. They probably won't want to cheat again anyways, and it would be nice to see some old faces.