RendureTextures - Ultimate CG Artist's Resource has a good sized catalog of High Quality textures, some seamless. Categories include water, Wood and Roof Tiles. Tehre are a lot more categories so if you need a excellent texture yoou can use i would start here.

License:

PRIVATE USE

You can freely use content in your own private projects and scenes. You can modify materials from this site at your own direction.

COMMERCIAL USE

You can freely use content of the site for the creation of commercial products in any form, as long as your product is not actually texture itself.