Have you seen Woot's postcard collection?
http://dearwoot.tumblr.com/ (no Dallas ones, YET!)
Tips: if you click on the slash on the bottom of the page you can search by username. Hovering over any postcard- if you click the plus sign, you can see the tags/username. And if you click on the very top one, you can see both the weird back and front, side by side.
You can still send some in! Our ultimate goal will be to have a wall of these when we move into our new Seattle building. They're getting to me a few days off when you think I should, but I'll update the link above with photos once I get new ones. Here are the addresses:
207 Boren Ave. N., 5th Floor
Seattle, WA 98109
4121 International Parkway
Carrollton, TX 75007