I've loved this concept ever since I first heard of it and they just expanded to Chicago, today. Basically, rather than waiting for a waiter to bring you your check or a bartender to close out your tab, this app cuts that part out and you pay and tip right from your phone. Excited to try it out.
They also have a PH promo code for $20 off: PRODUCTHUNT
Product Hunt
Whittl
Whittl