So there's this thing called the "Johari window." Basically you describe yourself using a few words from a set, let aquaintances describe you using the same set, then compare the results for some earth-shocking revelation.
And here's my Johari window -- fill it out if you have time! My Nohari window might be more fun though (thanks Wen for pointing this out) ;). If you're interested in this kind of thing like I am you can make one too, and I'll be sure to fill it out.
Add: The "bad" traits are in the Nohari.
Add: I see two glaring flaws: first, the provided vocabulary is inadequate (Ray pointed this out), especially in describing "bad" qualities; and second, people tend to be laudatory or at least anodyne on these things (note: this is kinda forced by the first flaw). I believe these flaws render this "window" unreliable for personality assessment. You might get a kick out of it though.