I just do Major.minor. Since I'm a single developer (with occasional help) working on a web app most people couldn't care less about the minor fixes that I make. So I just iterate up the minor versions as I put in new features and major version numbers when I make some whopper of a change/upgrade. Otherwise, I just ignore the small fixes as far as version numbers go (though I do have Subversion revision numbers if I need to refer back for myself).
