Android: Grabbing video clips from the internet is pretty easy. Getting it from live TV is harder. Clippit helps solve this by allowing you to create up to 30 second clips from live television.
The app has a limited range of supported channels at the moment, but for what it does support, it's handy. Simply select the channel and show you want to grab and sliders let you pick a piece of the show up to 30 seconds long to export.