archive.org is a fabulous site, especially if you're a Deadhead (I'm not). It has over 3,000 Grateful Dead concerts there - probably every one they've ever done.
I first came across the site about four years ago. I recommend everyone to check it out.
What's nice is that everything there is public domain, so can be downloaded legally - text, music and movies.

Wow. Just checking out http://www.nasaimages.org/ . Looks good.