I have gotten sooo many ideas and helpful information from this website I figured I should probably contribute what I have come up with...
Here are my save the dates that I sent out this past May. I have typed up how to instructions...let me know if you are interested and I'll post them.
I had to make almost 100 of them and I couldn't find enough of the orange sheets of paper, so I made them in 2 color schemes. The colors for my wedding are Orange (mango), Fuschia (watermelon), and light blue (pool)
On the back of each "pass" I printed "This is not a valid voucher" but I don't have a picture of that.
Thanks for looking!