I think honestly, and this is not meant to be insult, that the subject of realistic shooters is quite a narrow subject. There aren't all that many realistic shooters out there. Most of them are sci-fi. If it were a broader topic, it might be easier for someone to think of something to enter. As it is, I couldn't think of anything, at least anything recent other than the Medal of Honour and Call of Duty games.
A game competition sounds like a good idea. Make it a community ladder like the Babes of the Month, only this time you actually have members competing, and with something that many members here have. What about a Portal 2 competition in honour of Portal 2?
Another idea. We have a few people including me playing on Robert's Minecraft server. We could take screenshots of the different buildings and have people vote on them.