Art and science complement each other very nicely in this incredibly cool and simple paper kit to build an articulated horse by James Watt from Clockwork Robotics.  (Any relation to the Steam Engine linkage inventor James Watt?) It may not look all that interesting in the static photo above, but check out this video of the model in motion!

I've been fiddling around with all sorts of compressed-air engines over the past few years, but these Lego Technic engines by Alex Zorko are really something.   Check out these two examples, an inline 4 cylinder and a V8, each of which goes over 1000 RPMs.  You really can make anything with Legos.  Assembly instructions, parts lists, and live videos of the running engines after the jump.