Those of you that are into more realistic rendering with decals may be interested in checking out a great website I just stumpled upon. All textures are free to use (in accordance with the licence agreement) but your limited to 15MB / day.

www.cgtextures.com

The range of stufff available there is pretty amazing. Check it out if your interested. (I whipped up this highly technical piece of geometry and mapped it with a texture from the "concretes" selection) Rather proud of myself actually...