I have a Samsung A500 which uses SprintPC's 3G service.
I bought off of eBay a special USB cable that connects it to my computer and then bought a program called Snapdialer from fututerdial which uses my cell phone as a wireless internet access point.
It gets about 256K/sec which is quite fine for browsing the net. I used it a great deal this week (been traveling on business).
If you have a SprintPCS phone, I highly recommend getting set up on this kind of thing.