Some of the best free PhotoShop styles, imho, is made by a guy named Christopher Potter.
You can see some more details about the styles on Adobe Exchange, and you can download them if you have an Adobe ID. Since you probably don't have an Adobe ID, and i'm such a nice guy i have made a little zip (90MB) you can download from Rapidshare.

Link to Rapidshare file -> http://rapidshare.com/files/11252189/csp_photoshop.zip

Link to Adobe Exchange -> Adobe Exchange

You can see some examples of the styles below