Gmail for your phone!
Hurray! The ultimately cool Gmail client for mobile phones is out! Check out the Googleblog announcement or the actual download page. On my Samsung A900 it looks very sleek, with 6 message headers per page, access to my labels, a very easy navigation between various conversations and messages within a conversation, an easy way to see attached pictures (I've never tried the PDF attachment viewer).. If you have a java phone with some kind of data plan, you should definitely check it out :)