Google recently released a FANTASTIC Java app which allows you to easily check your Gmail from a mobile phone. It is very fast, simple and easy to use. To get it, just point your phone’s web browser to http://gmail.com/app . It will then ask permission to download and install a 100k applet.
Gmail has a lot of great features and enhancements through grease monkey or other plugins. The best feature however is it is accessible from multiple platforms including cell phones.