I just found out that T-Mobile is having a great promotion for FREE Hot Spot access on weekends for existing T-Mobile customers! Here's the link on how to take advantage of this: http://hotspot.t-mobile.com/freeweekends/. I'm pretty sure this is only good for a limited time but is a great opportunity for everyone to try this for free to see if it's something you actually want to sign up for.
This does work for pretty much all devices that supports WiFi (this includes my HTC Wizard!!).