One of the apps that comes preloaded on the HTC EVO 4G is Sprint TV, a service included in your data plan that allows you to watch live TV and other programming on your phone for free (more channels and content can be added for a monthly fee).
If you've never heard of Sprint TV before, then you'll probably want to watch live TV while you're on your way to work, catch up on an episode you missed while waiting in line, check out some new shows while in the bathroom, or sit on the couch watching something else while your family has control of the living room TV.
And you can do all of that on the HTC EVO. Just don't expect to be able to do it on a WiFi connection. While many media streaming apps will often only work on WiFi, which tends to outrage customers who want to access the content on 3G, Sprint TV only works over 3G and 4G.
I hope you've got a speedy connection!