Some texture websites that will satiate 99% of all your texture needs
Mayang's Free Textures
If you cant find what you need here, then stop looking. Its not on the internet.
Textures and Backgrounds
Not a huge selection, but well organized
LOTR Textures
Some very different types of textures you may not find elsewhere
Seamless Texture Library
Posted by Caius Britannicus
Stone Textures
Stone textures broken up into specific categories (i.e. Sandstone, Granite, etc)
GRSites
Posted by Arbaces
Stockvault
Moderatley large 'vault' of well organized textures
m3corp
Posted by vikrant1986. Boasts 3d textures as well as tutorial on how to make them.
MetalCity
Easily browsable thumbnails dividing by category
Sub Dimensions Studios
Posted by b.bonetto, a seamless texture library
****If you know of any other good websites that host textures, please post here and they will be promptly added to the list. Thanks ****