Cruising around the MTG Salvation forums today, I discovered a topic about where to find quality playmats for Magic: the Gathering. One of the posters supplied a link to InkedPlaymats.com. You can purchase playmats with featured designs, generally for $20 plus shipping/tax, though some are listed at $25. But the real draw for the site is the ability to buy totally custom playmats for $25 ($35 if you want the InkedPlaymats guys to do a proof or any editing to your image).
You supply an image file (many file formats are accepted: PDF, CDR, EPS, AI, PSD, TIF, JPG, and even hardcopy via snail mail if you're willing to pay a $10 service fee), and they ship you a 24x14" playmat (machine washable!) with your image printed on it. The InkedPlaymats website has a downloadable PSD template with guides to help design the image.
The whole operation seems pretty sweet, and I've already ordered two playmats with two different images of my design. One mat goes with my five EDH decks (both complete and under construction). The other is a play on Skithiryx, the Blight Dragon; the image of the dragon itself has been adjusted to be bright and colorful, and a rainbow passes behind him. This is now "Skittles, the Bright Dragon". Along the bottom, the text reads "Taste the Infection". Along the left reads the same text, written in the Phyrexian language.
