To a large extent I rely on sametime and my mobile phone (a really dodgy old nokia - kudos points only for the antique value).
However for those times when you do need to access email - I thought this looked kind of cool.
Domino 8.5 beta 2
Interestingly I composed an email using Chrome and could see th received email in Lite and Ultralite mode - but not in Full mode. Then again it was in a win2003 vmware