Finding high-quality brushes to use in your designs can be quite a challenge. Fortunately, there are two exceptionally fantastic websites that provide some really great free photoshop brushes.
Brusheezy
One of the more well known photoshop brush repositories, Brusheezy is great for pretty much any category of brush. Fast and free, the site’s only downside is the somewhat clumsy brush submission process.

QBrushes
Spend a few mintues on QBrushes and you are sure to find a brush for you. While specializing in grunge and splatter brushes, there is still quite a variety to be …

Digital Revolutions has created a pack of 12, high-resolution, grunge brushes. These are some incredible brushes and PSD Nation recommends that you check them out.