Have a series of orthogonal tags: - "own" / "want to buy" - "played" / "want to play" - rank them on how much you enjoyed playing 'em.

A UI that's cleaner than BoardGameGeek's, but not as "clean" as the new Reddit interface. Functional, but not smoothed down for a toddler. UX matters - I shouldn't have to click three times to add a game to a list/tag it/etc. (ahem, Goodreads.)

I fully don't care about any social element of this. I've got my own way of asking friends whether they want to play a board game with me.