New Balance is great; not all of their models are vegan, though.
These websites have a nice selection of vegan shoes & sneakers (and other veg stuff!) and good customer service/returns:
www.veganessentials.com
www.pangeaveg.com
www.veganunlimited.com
www.alternativeoutfitters.com
www.thevegetariansite.com
I have ordered stuff (ranging from shoes to vitamins to bumperstickers to foods) at all of these stores and have been very happy.
