Changing your default DNS addresses may speed up your mobile browsing experience and is free to try. Many users have seen improvements with T-Mobile's data connection and it can't hurt to at least give it a try.
I surf quite a bit on my mobile devices and am actually satisfied with the EDGE data speeds I see most of the time on my T-Mobile unlimited data account. It is tons faster than the way I used to connect wirelessly a couple years ago, but it is a bit disheartening to see everyone else getting 3G wireless data speeds while T-Mobile is a bit quiet on their plans. I was made aware of an interesting thread going on over at MoDaCo that shows how you can change the DNS settings on your mobile device that may speed up wireless data speeds. It seems that T-Mobile in particular has DNS addresses that are a bit slow by default and using DNS settings from OpenDNS or OpenNIC appear to provide faster browsing. I updated the DNS settings on my Nokia E61 and am testing out the speed differences at this time.
The MoDaCo thread has details for Windows Mobile Smartphone and Pocket PC Phone Edition devices, but the same DNS changes can be made to other mobile devices. On Nokia S60 3rd Edition devices, first make sure you device is offline and then go to Tools>Settings>Connection>Access Points and then select you wireless data access point. In Edit mode select Options>Advanced settings and you will see the 3rd line down allows you to specify DNS addresses. After you enter the primary address the secondary one will open up for editing by default.
Chris Pirillo talked about the DNS trick for Windows computers last month and also has a tip for faster surfing with FastCache. Check out these methods and see if your wireless browsing experience improves.