Mr. Potato Head is one of those things that lends itself well to endless variations. You can go to any decent toy store and pick up...
Darth Tater and Spud Trooper:
Idaho Jones (of "Taters of the Lost Ark" fame ):
But the best version I've seen yet is Steampunk Mr. Potato Head, not least because he's homemade. Childhood nostalgia combines with geekery to make WIN.
Find out how to make your own here.