I've used the HD PVR
from Hauppauge for a few video reviews on the site. It's a pretty cool USB recording device and one that has really been reliable. Hauppauge is gearing up for a new version and it looks to have a few nice improvements
The Hauppauge HD PVR 2 Gaming Edition
expands on the original one by adding both and HDMI input and output allowing you to record 1080P video at 30FPS. Dropping it down to 1080i will let you record at 60FPS. It's got a nice button on the unit to initiate the recording and the software it comes with will allow you to edit the video as well as upload to YouTube easily.
Check out the unit in action at GamesCom.