Yahoo E-Mail
I probably mentioned this to a couple people at work but if you don't already know about this check it out! Yahoo has re-vamped their email program and made it a competitor for gmail. Not only do they offer the same space for your account their site is completely ajax driven and has a familiar look and feel as outlook!!!! In terms of user interface it kicks gmail! In terms of speed it isn't as fast as gmail but you won't be disappointed.
Since it is in beta there are still some bugs being worked out - but not too many :-)
Do you Yahoo!?