There are a lot of smaller, less known, visual style websites on the web. One site that was brought to my attention is WinModify.com.
Winmodify does not have the largest selection of visual styles. But it has a very good selection of quality hand picked visual styles. It often seems that the larger sites include every style that is submitted in their index. This makes it difficult to find some of the better looking sytles that are made by more talented artists.
Check out WinModify.com for a good selection of quality visual styles.