Personally, I don't feel that a forum does a great job of helping GMs find players or helping players find games.
I noticed that there is a game search, but that doesn't seem to work very well. I assume it works by searching campaigns that are already in progress, but that really isn't the best way to do it, because a lot of times I think the GM won't even have the campaign actually started on the site until they start putting together the party.
So that is why I propose a separate tool to bring GMs and players together in an organized manner. The GM can post a game with all the details involved (Game system, days/times playing, character creation outline, number of players needed, ect.). Players can search for these posted games by the criteria listed. If they are interested, they can flag themselves as such. When the GM looks at the post he/she can see a brief outline of the players that are interested, and they can also flag any of those players as accepted (perhaps requiring another confirmation from the player). Once the number of needed players is reached, the game will be listed as full (it will not show up in search results anymore).
Each of these posts would also have their own comments so that details could be discussed, but you would not end up with a huge list of people just saying they are interested... if you are interested you just click the button. And once games are full, they are removed from view of everyone not involved so that it keeps things from being cluttered.
These are just my initial ideas on it, of course a lot of these things could be improved upon. I know that the dev team here is probably very busy, but to me this is an very important thing to consider. A game cannot be played if it cannot be started in the first place. Having a smooth, fluid, easy-to-use method of getting a campaigns started will only help the Roll20 community expand further.