Do a search located at the top of the page, there are some many options out there for you as far as applications go. Nextel will not allow you access to the Blackberry Browser, but there is an full HTML browser that should cover you in that aspect and it is faster.
www.reqwireless.com
They have email viewers as well as webviewer. There are a lot of post on these subjects, make sure you exhaust them because some people don't like to answer repetitive questions. Just an FYI. :D