I was in a guild wars guild that was extremely active during the Alpha + Beta for the game. Since most people (including me) were not actually in the full time Alpha / Beta we hung out on the forums and had an extremely active forum.
There were about 15-20 of us who were really active, then suddenly 1-2 weeks before the game came out we lost 5 of our most active people in quick succession, then the people who had been in the Alpha / Beta and had started the guild got sick of the game and quit, then WoW was released. All those things really was like dumping the forum (and guild) into ice water. After that we never really got any new members and the forum slowly died. (you can still see a remnant over at
www.ridethestorm.net, its a ghost town). At the very end there were about 5 people still semi-active and 4 of them moved onto WoW, since I knew WoW would be gaming crack to me and I didnt want to pay a monthly fee I stayed away.
In any case I think one of our biggest mistakes was not finding a way to direct traffic to the website. In order to gain new members you need to have a way for new members to find your website and, this is in my opinion the most crucial, you need to be active in welcoming them to the community.
The way our guild had really gained lots of members is they made a post on a larger Guild Wars forum saying, "Hey if you are interested in a mature community of gamers come to
www.ridethestorm.net " I dont know if any of yall are active on any larger TF2 forums, or some other gaming forum, but if you are it might be a good idea to make a post directing people here if they want to learn more about creating custom maps, find new custom maps, brainstorm, and / or just hang out. Maybe in your postings to FPS bannana you can drop a link back to
www.tf2maps.net at the bottom of your map postings (before the change log, who reads the entire changelog anyway?) or maybe someone could make a post somewhere on the Valve forum directing people here.
As many of you know I am not really a mapper but I do really like to play custom maps and if I have a place were I can both get the hookup with fun custom maps AND offer feedback that makes the maps more of what I like, then its a Win-Win for me. And in final thoughts I really dont want this forum to go the way of the dodo bird (not that I think it will)
Sorry for the meandering reply but I have a lot of thoughts swirling around and I just kinda started typing.