TV.com (app) - CBS and Showtime Streaming on your iPhone
How bout CSI Miami full episodes streamed to your iPhone, legally... for free? CBS Interactive's TV.com give you just that. There aren't a ton of shows up yet (at least not full episodes), but CSI, Star Trek (the original!), and Gossip Girl (you know you've seen it) are all there.
TV.com (its an app, AND a website!) allows you to create "feeds" of shows you'd like based on keywords. You put in a few shows you like or terms, and the app creates a specialized feed of content you'd enjoy.
I'm sure more full shows will be coming quickly.
The app works over WiFi or 3G, and is available now for the low low price of free in the AppStore.