DB has made a lot of cool robots. He's kind of The Original Mr. Roboto. For background
information, you can also take a look at the lynxmotion site. They have a number of
walkers shown, and the Brat style is relatively simple to build from scratch.
http://www.lynxmotion.com/c-1-products.aspx
http://www.lynxmotion.com/c-85-bipeds.aspx
Adding to what cr0sh said, the big thing with walkers is, you need strong servos, and
the more joints in a leg and the longer the legs are, the stronger they need to be. The
robot has to carry its frame and also its batteries. This is the most serious issue - some
people get carried away with making fancy frames out of aluminum/etc, and then the
servos can't lift it up. In addition, as the #of joints multiplies, the complexity of the gait
software goes up "much" faster.
cr0sh already has you thinking of things that can keep you occupied for the next 4 or
5 walkers down the road, ;-). The best thing is to start simple, and learn a lot, and use
that knowledge to springboard to the next walker.