Gomediazine.com have published a set of 5 free awesome textures.
The five textures are grungy and cool-looking, and come in the .JPG format.
Of course, they are free to use for all of your projects.
Their dimensions are circa 2000×1500 px.
You’d use them for existing designs, and for “indie” homepages–but they’d probably fit video games better.