While the turnaround time wasn't quite as fast as expected/advertised, I am really happy with the postcards I got from PrintsPal.
I placed the order via the website on a Thursday afternoon, approved the proof that night, and had them the following week Friday. While I was hoping to have them by Wednesday (they're my wedding invite RSVPs) the shipping time wasn't too bad.
The quality of the color, the printing itself, and the nice weight of the cards beats almost anything out there for the price. I totally recommend this place if you need postcards or business cards or other little printed things!