One of the most popular products I offer my client are the digital negatives of their images. These are essentially the single most valuable item I offer- since they are the actual images themselves. And really, I can't imagine being a bride in 2012 and not having your digital negatives. After my clients receive their digital negatives a question I hear frequently is "do you have a suggestion on where to print them?" And my answer is "Yes!".
To be honest, if you would have asked me 4 years ago where to get custom Save the Date and Thank You cards made I might have avoided answering. There weren't a lot of great non-cheesy options out there. Finally, though, I don't have to worry about what disastrous things will happen to my work when used as a Save the Date or Thank You card.
Here is my recommendation- WeddingPaperDivas.com. I made these examples within about 30 minutes on their website. Navigating the website was super easy and I found the design styles to be everywhere from classic, to romantic, to fun and quirky. Loved it.
And some of their Thank You cards...I could have designed these all. day. long.
One of the coolest things about this site is that many of their designs are part of a matching set, so you can begin with your Save the Dates, and do invitations, programs, thank you notes, and keep everything in a consistent style.
So good luck, ladies! And happy creating!