(Click on image to see it bigger)I like the example above (picked up from BoingBoing) for the obvious music business reference and also the fact that it exposes Warhol's address as being only a few minutes away from where i currently live.
"Letters of Note is an attempt to gather and sort fascinating letters, postcards, telegrams, faxes, and memos. Scans/photos where possible. Fakes will be sneered at. Updated 2-3 times every weekday."
Here's another of my personal favorites written by Albert Einstein "The word God is the product of human weakness" and it's original source with even more incredibly interesting commentary here at Search magazine.