Nathan sez,
In the early morning of March 21, JJ Adams, assistant editor at The Magazine of Fantasy & Science Fiction asked some "con-loving web savvy fan" to build a convention finder that allowed people to find nearby conventions when searching by zipcode…
By 10:23PM of the same day I submitted this, to his general approval: Convention Finder
Now, it has to be filled with conventions. Spread the word to your various fan groups and/or, if you know of a convention that's coming up in your area that would be of interest to geeks in general, please feel free to submit it yourself to the convention finder (just make sure that you have the venue's zip code).
(Thanks, Nathan!)