Gizmodo just ran a story about the awesome Lego tanks created by Stijn Oom who is only a 14 year old kid from the Netherlands. Stijn started to play with Lego right after he was potty trained (literally). Just a short time later, he's a certifiable Lego genius. He builds the best Lego tanks I've ever seen.
The accuracy he achieves is astounding. See the following tanks build by him and you can see more of his creation in MOC Page.