I found a really awesome site for free textures lots of great stuff easy to navigate plenty of different usage and surface types. All raw textures though and some need cropped and manipulated for your usage but I figured I'd share.
the first page is just random textures but if you click textures at the top it takes you to a view page with categories on the side.
also has brushes to use with your art program so if you want to add some scuffs or a crack to your wall, ceiling, floor, ect. you can use those.

http://www.plaintextures.com

Below is an Image Manipulation program, it is free and open source, supports photoshop brushes and plug-ins

http://www.gimp.org

also it supports DDS but you have to download the plugin for DDS here: http://registry.gimp.org/node/70
Hope you enjoy!

Great topic, thanks for posting.

Another good resource for textures is http://cgtextures.com

Great topic, thanks for posting.

Another good resource for textures is http://cgtextures.com

this is a good page, from here i get a lot of textures