I have to say I like this one MUCH more than Harry Potter. We bought a copy of this book today at ICA.
If you crossed a comic book with a kid-oriented version of Make magazine or maybe Bill Nye the Science Guy, you would have HowToons.
I'd seen the site before, but somehow wasn't aware of the book. Miles loves it and is already working his way through the various experiments/projects, the first of which was one-handed rubber-band shooting.