Stretched, scratched, dirty and rusty, grunge is one of today’s popular web design/ graphics styles.
Below are a few hand picked sites which offer grunge style backgrounds and textures to download and use on your web site.
UrbanDirty – 300+ photos of grunge textures, a fantastic resource.
gallerie1.de/html/metall.shtml – Metallic rusty textures.
Textureking – grunge, dirt, plaster and more.

DeviantArt Textures.
Texturebin – Many textures here.

10 Grunge, rusty and dirty tilable textures at PhotoshopRoadMap
texturez.com – Free stock texture photos in high resolution.
Feel free to add to this list if you come across any.
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Please let me add texturez.com to this collection
Thanks Tom, site added.
Amazing work!!!
Thank you! Extremely helpful.