I think my favourite freebie character of all time is Splud, from 3DU. He's no longer available, sadly, and he does have his issues in the rigging (which, over the years, I've been able to correct as I learn more and more about rigging myself), but he's just such a gosh darn neat little guy.

This is Spluddie with a specially-made texture as a prezzie for a friend who works at the company that built the Canadarm.

docandraider.com -- the collected cartoons of Doc and Raider