Showcase - a few different ways it can be used, PC gallery section, reviews, articles...
Competitions - from AvForums - just got this and I think it's great, easily do game giveaways for upcoming games.
RM - guides, tutorials, files ect...
What we originally did first starting out was to get into a game that was very popular, DayZ ArmaII mod. Sometimes you get lucky and things just take off. Hopefully you have a good group (4-5 people) that like discussing stuff on the forums, really helps kicks things off.