Raffles, giveaways, and contests, whatever you wish to call them, are a great way to increase traffic on any forum.
Define a different prize image for each raffle.
Set raffle rules on a per raffle basis.
Set raffles to start in the future or on the day you create the raffle.
There should really be a giveaway addon, much like SteamGifts or GameMiner
Example: You have it set up so at the end of what ever time/date you put for the giveaway it will choose a winner from everyone who registers for the giveaway (Which would also allow currency like [bd]money). You could...