You post a topic, list, category, whatever, in my comments section. (examples: "5 Sexiest Things About Ron Weasley" or "Top 5 things to drink"). Then, in a separate post, I'll post the answers to all your Top 5 ideas, according to me. Then you post this offer in your own journal.
(It might take me a few hours before I reply though as I'm eying up my laptop with the nasty thoughs of playing Civ4 again....someone stop me now!!!)