Just thought I'd share something I just worked out.
There was a thread in here somewhere that talked about brick materials. I use the Acme Masonry Designer. http://www.brick.com/md/index.htm
It's a great tool to create custom brick patterns. The problem is, they aren't seemless. But I just figured out a simple way to make it seamless. Just crop the image in photoshop or, if you don't have that, the basic windows picture manager works too.
Crop it just to the leftt of the first mortar joint. On the other end, crop it just to the left of the mortor joint. Basically, you are leaving the mortor on the right side and getting rid of it on the left. You are also making the brick pattern on the odd rows start and stop with a half brick.
The results look great to me. I can't tell where one stops and the other begins. Best of all it's free and easy.
Acme Masonry Designer also creates an alpha .png for your relief pattern. Do the same to this image so the joints line up.
Hope this helps you guys.