I love geeky science web sites. Via Science Magazine's site, I found this collection of rocks that people have thought were meteorites; by clicking on the pictures, it tells you why it's probably not a meteorite.
I also love geeky science memory aids. One of my favorites is from Scott Adams, writer of Dilbert.blog, discussing how to remember the difference between stalactites and stalagmites:
"Remember, stalagmites might stick to the ceiling, but they don't"