Google have a couple of J2ME applications for your phone that are really cool.
The first gives you access to your GMail account. It’s really easy to use. Just browse to http://www.gmail.com/app with your phone to download it.
The second gives you access to Google Maps. The travel directions are great (although it can be a little messy to type in addresses on your phone). In certain parts of the world it will even show the heavy traffic reports overlaid on the maps ! Point your phone at http://www.google.com/gmm to download it.
Remember to make sure you have some kind of data plan for your phone otherwise it will be very expensive to use these applications.