Check out www.r9chc.com. She makes custom saddle pads and has a ton of different patterns on there that you can order. I ordered one of the "Maverick" series with a bunch of embroidery. I haven't gotten it yet, but her stuff looks awesome. She was willing to match it to some custom tack I had made by www.uniquelyequine.com. I love the custom stuff!
I also ordered a custom Christmas saddle pad from "GypsyTally921" on here. She usually makes custom bareback pads but she was willing to try her hand at a custom saddle pad for me. She took pictures of fabric options and made it the size that I wanted. It is really nice. I'll be using it tomorrow and plan on posting pictures.