A great piece about the creation of Chewbacca (it turns out it's a little more than George's dog, Indiana):

Chewbacca, the character, also started his life in the rough draft (May 1974) as a kind of barbarian alien prince on the jungle planet of Yavin:

 

...The eight foot Chewbacca, who resembles a huge, grey bushbaby with fierce baboon-like fang...

The article has great background on the development of Chewie's appearance and story arc (or lack of unless you subscribe to an alternative interpretation) along with great concept art and costume images.

I think my favourite image is this one of Ralph McQuarrie's where a Storm Trooper is wielding a lightsaber:

Also for anyone who's interested: with Jabba as a human gangster with an Irish lilt.

(via Kottke)