GMAIL

Gmail by Google. It isn't the most robust mail service, and currently is only available via your web browser (unless you run a third-party application). Still, it has 1 GB of space for you to use. It is still in testing, but is very popular. I moved over to it about a month ago for my non-work stuff. As for now, it is an invitation-only affair.

So, if anyone wants to give it a try, email me or post a comment. I have three invitations left (for now).