Alright M&A, I saw this on another forum and it was incredibly successful, and is a ton of fun to play! How it works is that someone says "the photo below me..." and then describes something. The next person to reply must post a photo that matches the criteria, then says new criteria for the poster after them, etc. I think it could encourage people to go out and shoot pictures and maybe motivate them to get off of their couch. Try to limit file pulling, but for the first couple people I guess its ok.
Example: TPBM deals with music
My picture is a shirt I got at a concert
The picture below me deals with fall/autumn. go!