Well I think I could make a Mod to do this, but there's no telling where the settings are for this.
Then if it was a Mod, you'd need have it on the back end to make the changes. However, I think this should be in Look & Feel, because there's nothing else in that area that worth having there lol
Or better yet, why doesn't it just size to the white area? If you look at my current site I'm working on, We made this Mod for the front page that uses the Category listing and it looks like this because the Thumbnails are so small! It makes it difficult to see the dogs.
http://i21.photobucket.com/albums/b298/fasterthanyours/frontpageexample.jpg
I'd also like to know how to change the Category listing to 2 columns that take up to whole width of the same area.