Zmescience.com posts the 10 most amazing unexplained artifacts. I've read about most of these in numerous places, but the very first one on the list is new to me, could it be Thor's hammer?
Top 10 unexplained phenomenon from aquiziam.com. Some of them aren't so mind blowing, but finding a toad in a piece of coal(or rock) has always been one of my favorites.
Another good top ten list from listverse.com. If you think you know all of the weird things that happened in history, this one will probably surprise you.
This site goes into detail about a number of archeological oddities, and then does a good job at debunking them. So whenever you read an article about some mysterious object found, go to this site, and it'll probably have a perfectly logical explanation for it. But if you like the mystery, steer clear of this site.
Nationgeographic.com has a wonderful article about Gobekli Tepe, built approximately 11,600 years ago in Turkey, it makes archeologists rethink their theories of when civilization began.