A good source of textures?

I am looking for a nice but affordable (or free!) collection of textures and backgrounds to use in creating web store advertisements. I need something with the following themes: mechanical (bolts, steel, tires, motorcycles), fire, leather, and anything else cool.

I could probably create many of these myself, but this is a high volume job, and I need something quick and clean.

Any recommendations?

This site has some great links, here's the textures section.

http://www.pixelperfectworld.com/links_patterns.htm

http://www.bluevertigo.com.ar/bluevertigo.htm has also links to a lot of photography sites.
Another endless source of images is investing in a cheap digicam...

I wouldn't recommend a "cheap" digital camera if you are going to use it. Get atleast 2 or 3 megapixels. I've had great experiences with a Fuji digital camera.

It's all on what you need. If you need textures that the average website or stock site wouldn't have, get a digital camera and take a picture of it yourself. Otherwise, just try to find it on a good stock photography site.