And moreover, is the discussion of such classifications considered Nerdy in and of itself? My friends and I just had a discussion on this, and we disagree on the terms. But here's my take ...
These classifications are in pop culture, and that's where I try to match definitions ...
Nerd -- Intellegent, and a fan of one or more of the Sciences (math, physics, etc), with weak social skills. Nerds are compatable with Nerds, though. Think Revenge of the Nerds. (#1, not #2).
Geek -- Enthuiest and Expert in any domain (Audio, Cars, etc). Not necessarily weak in the social area.
Dork -- Weak social skills and into "dorky" things like D&D, Anime, etc. Not necessarily smart, most definitely lacking social skills. Dorks have a hard time interacting even with other dorks.