What is everyone's opinion on the usefulness of shop by brand on an ecommerce site.

http://www.rei.com/brands
http://www.gemplers.com/shop-by-brand
http://www.tgw.com/main.jsp (pull down on homepage)

Forgetting about any SEO implications, does providing a long list of brand names help the user? Will people actually shop in that way (I want something made by Nike, but don't know whether it will be a shirt, bra, weights, or basketball, just show me all Nike stuff)?

Shop by Brand seems to be on almost all eCommerce websites, but just doesn't seem useful to the consumer, especially when most of the brands are small, unknown, and may only make one product.

What are your opinions?