Other features of GMail include a potent search engine, and the ability to access your e-mail both through POP3 and Web site. >
Registration is only available through an invitation, but it is not hard to get one.
As a big fan of GMail myself, I should also point that they bit the competence once again with the latest addition of their full HTML editor. Once more, they came up with the fastest, smartest HTML editor I've seen in a web site.
Indeed, what they use to make the service web interface SOOO slick is a technology cocktail known as Ajax, which I truly believe is the way in which the Web will evolve tto provide richer interfaces in the mid-term.