I got signed up as a beta-tester for gmail - Google's e-mail system. Great interface, with 1 GB of storage. So far, I like it. I'm guessing it doesn't allow any kind of POP access, though. The interface isn't as mature as Yahoo, doesn't have any of the toolbars or thick client tools to access it, but it's new, and based on google's track record, should be great eventually.