Running a bar-tab's problematic: closing out can take forever, and there's always the risk someone uses it to buy the bar a round of shots, a move credit card companies might call "priceless", but that you consider "really, really expensive". Saving you time and worry, Tabbed Out
The brainchild of an Austin-based theft-prevention software specialist, TO is a free-download app that allows you to remotely close out tabs by sending point-of-sale systems the credit-card info stored on your iPhone using 256-bit AES encryption, which apparently is a whole lot of encryption.
To start a tab, just select from the list of participating bars/restaurants and flash your server the generated code; using the "bill details" tab you can monitor the mounting damage throughout the night, then, at the point where another gin & tonic becomes counterproductive/legally unattainable, add a tip and press "Pay" (or take advantage of not having to lock eyes with the bartender, and prickishly press "Pay").
If you're expensing the night, or are the the last man on Earth to actually balance your checkbook, upon request they'll email a copy of your receipt; either way, each use comes with a $0.99 convenience charge, a figure cunningly arrived at because it's 1-cent less than a dollar
As for bars/restos, it's totally free to enroll, with current beta-testers including east-side notables (Shangri-La, East Side Showroom, Rio Rita), fancier eateries (Jeffrey's, Cipollina), West 6th watering holes (Annie's West, Kung Fu Saloon), and downtown music venues like Mohawk and Beerland -- a vacation to which you might consider priceless, even though your HMO deems it really, really expensive.