This is a guest post by Jesse Anderson from EchoFaith.com. Make sure to check out his site, he has some great stuff, especially "Texture Tutorial 01 - Seamless Grunge Textures". The textures below are totally free for any and all use including commercial, no attribution required.
The pack includes 14 concrete/grungy textures that are around 2100x1500px. Just click on the images below to download the individual textures, or download them all in a zip file at the bottom of the post. Enjoy!