I have a bunch of Legos stashed up from my youth. Didn't really do anything with them for a few years, maybe because I'm more of a Warhammer person now (the WH models are much more complex and much more customizable then any Lego one).
I saw many things made out of Legos. I believe I remember some sort of action figure thingy I found on the net some years back. Think a plan for its basic structure might still be floating around my HDD.
And then there is
LEGO MECHWARRIOR... (if you never heard of it,
check this link - wholeheartedly recommended)