Anyone do STD postcards?

I would really like to do a postcard. FI likes them better than magnets (both are fine by me) and I like the fact that a postcard stamp is only 0.23. (I can be really cheap!)
If anyone has done them... do you have a pic? or where did you get them if you liked them?
If you didn't do them... what is your opinion of them as opposed to magnets?
Thanks!