Is there anyway to search for an email address for people you know?

I've found people here before:
http://www.internetoracle.com/find.htm

The other way I've found people is by simply googling their name (try first name first, last name first, with and without middle initial) and seeing if there's a web page that's got them on it.

It's a bit of a crap-shoot for finding that sort of info, but both are good first efforts to try.