We approved the purchase of business cards for the HacDC board and TimS bought some LivingSocial/Groupon discounts for VistaPrint to print them. Here are the Inkscape design files: and .
The coupons actually do help on the price but not as much as one might think because larger percentage discounts are available without them. Net cost was about $17 for 250 glossy two-sided color cards or 500 matte cards.
The QR code was generated by http://zxing.appspot.com/generator which I found gave a smaller payload than http://www.qrstuff.com/.