You post a topic, category, list, whatever in the comments. (examples: "5 Times Roy Mustang Nearly Got Arrested", or "5 Books Alfons Heiderich Stole From the Library"). Then, in a separate post, I'll post the answers to all your Top 5 ideas, according to me. Serious or fun!
Slash, femmeslash, het, gen, it's all fair game to me (just warnin'). :) I'll do as many as I can.
ETA: Woo, thanks guys! I think I'll have to close this for a bit, and try to finish all the ones you guys gave me. I'll see about opening it up again once I finish the ones already down there.