It is almost impossible to work on a 3d project without using any kind of bitmap-based textures. Most of us try to pick some textures on search engines like Google. But, did you know that not all images are allowed to use for commercial projects? You can't simple pick a texture and use on a project. You have to either create your own textures, or find a library without any restrictions to use for commercial projects. If you don't have any reference for a texture library with no restrictions for commercial use, you should take a look at Texturelib.
The site has a great collection of free textures, and according to a statement about the usage of all textures, they claim that all textures were made by for Texturelib and taken by their own cameras. So, there aren't any restrictions on the use of textures for commercial work.
There are options to download the textures with diffuse, tiled, normal and specular maps.
Go check it out!
Maybe you didn’t read the license, it looks pretty hostile towards free software so please do not use them.
http://texturelib.com/license
What exactly is hostile in the license? Do not distribute someone else’s original work. Make some product using those images and distribute it freely. Just do not distribute original images themselves.
It means you can’t use them in for example an open source game to be uploaded to Debian/Ubuntu.