I googled "pet friendly housing in Austin, texas" and this result was #1:

http://www.peoplewithpets.com/states/austin.asp

Along with a few others...

http://www.austin-apt-locator.com/PetFriendly.html
http://www.aptselector.com/austin/au...partments.html


This site though seems geared specifically toward housing people with pets:
http://www.peoplewithpets.com/

Good reference for anyone to have I guess!