I've listed a ton of places to get Photoshop Brushes in the past. Today I have yet another to add to your bookmarks.

PSBrushes has categorized thousands of Photoshop brushes along with convenient preview images for your download enjoyment. Categories like Grunge, Space, Plants, Oriental, and Fractals make it extremely easy to find exactly what you're looking for. Some of the sets are quite large, containing over 80 brushes each. Others are smaller and very specific, with only 8 to 10 per set. All are quality sets.