Building simplicidade.org: notes, projects, and occasional rants
Another puzzle by the Bram Cohen (the same who created BitTorrent) and Oskar van Deventer: the Geary cube.
Some of their previous puzzles are very interesting like the JumblePrism or my two favorites, the RotaCubes and the Bramboules.
Oscar van Deventer creates stranger things: the WimTvane or the Topsy Turvy are just two examples
He also has a beautiful adding machine for kids.
I like puzzles. Puzzles good.