Here's another puzzle from the Cast series by Hanayama, the Cast Laby:
The Laby consists of two solid pieces. The larger circular piece that is laying flat (that I'll admit isn't brilliantly pictured here) has a maze on both sides, and if you look very carefully the other piece has two pins that can run in the mazes on both sides simultaneously. Your goal is to detach the two pieces from eachother by navigating the mazes.
Now this is a good example of a puzzle that looks incredibly easy.....but isn't. I think it took me around half an hour to solve the first time, and now I can do it in a matter of seconds. There is only one route through the maze to complete the puzzle.
Another great one to hand around to friends.
Where I got the Cast Laby from: Puzzle This. And it is also available from Puzzle Master.
I didn't actually buy this one myself as it was a present, but I have it on good authority that it came from Puzzle This. Probably.
Also read Brian Pletcher's review of the Laby here: LINK