I was fortunate enough to get an invite to open a Gmail account from my friend Scott Ladewig.  Gmail is Google's answer to Yahoo, Hotmail and others: free internet-based email for the masses.

I'm generally a POP3/IMAP sort of guy and avoid web-based email, but the convenience of a solid web mail solution with a nice interface is very attractive.  That's why I joined Oddpost about 9 months ago - it has an amazing web-based interface (IE only) and decent enough IMAP/POP3 support.  As good as Oddpost is, I've moved everything over to Gmail and plan to stay there.  Several reasons:

• Oddpost has had some notoriously bad outages.  Service has improved, but I still see more downtime than I should.
• The client is a bit buggy. I've had a number of Javascript issues, mostly (IMO) due to synchronization challenges.  I don't think Oddpost likes IMAP clients very much.
• The way Gmail handles conversation threading is groundbreaking.  I liken it to gmane, though I think Gmail is even better.  I subscribe to several high traffic email lists, so by managing the threading effectively Gmail lets me filter out a lot of noise.  If don't care about a particular thread (like the rules arbitration for Goa and Maharaja happening on spielfrieks right now), I can delete or ignore dozens of messages at once my skipping a conversation.
• Search.  It is Google after all, right?
• Tons of storage.  1GB for now, and I doubt I'll need more any time soon.

My major complaint right now (like others): lack of POP3 and IMAP support.  Hopefully they'll offer a paid service with this support in the future.