Sometimes we come across a tool so incredibly useful that we just want to hug the person who created it. Keepvid.com is one of those; you paste in the URL of a video you happen to be streaming online, and the KeepVid service will return some download links you can use to grab your own copy.
It’s simple, helpful, and there’s even a bookmarklet for your browser so you can use the service without visiting their site.