But that's not a requirement. I won't go into the properties and virtues of a good logo, since if you're the kind of person that could come up with a great logo, you'd know them better than I. Though if I had to give any direction (aside from the scurvy bones logo above), I'd say that I really love farseer's logo:
It's so simple, and iconic ... and explains exactly what the farseer physics library is all about.
What will you win? aside from my undying gratitude ... the winner will be forever recognized (with a link and info on any scurvy media distribution site) as the logo's designer.