Skinit. Their eCards are instantly delivered, and then the recipient can pick out exactly what they want, whether it's a photo skin or a pattern.
I had a chance to review the site, and it was easy to use. I opted to get a pre-set pattern, because my daughter absolutely loves jungle cats. The pink leopard spot skin we picked out fit my Kindle Fire perfectly. It was easy to apply and fits securely, so it isn't likely to fall off, even with frequent use. The website is easy to search for pattern ideas (I searched for cheetah and got a variety of leopard and cheetah prints). It's also nicely organized by theme, so if you have a certain interest in mind, you can browse through categories like sports, comics, pop culture, art, lifestyle, patterns, and specific collections. You can also get metallic, carbon fiber, or glitter skins; or, of course, create your own.
The shipping time was fast, and the prices are very reasonable. It's a site I would definitely consider using again the next time we get a new device! Now is a great chance to buy, with 30% off cases and skins with code PRESIDENT.