In my completely unbiased opinion, Erik (age almost-4) is pretty good at Lego. He has a good attention span for it, and he comes up with designs involving shapes, symmetry, and color that I just wouldn't imagine.
Lego seems like a nice hobby, so I'd like to help him develop his talent for and enjoyment of it. So I figured it would be nice to get him started on more involved projects.
Do you know of any book or other resource about having more fun with Lego? Preferably not in the "buy expensive movie-licensed sets with a tiny number of bricks" theme.