Anything you want, delivered within an hour. Yes, ANYTHING.
Somehow not developed by Hakeem Olajuwon and Ralph Sampson, Postmates Get It Now is a rad new iPhone app that takes a local business-to-business mobile shipping service (Postmates) and hacks it into a pan-SF business-to-you deliverer that'll almost instantly mail-man anything in SF to your place -- from refrigerators, to birthday cards, to... refrigerators with birthday cards already on them [cue world-exploding-and-collapsing-into-itself montage]
To use this puppy, exit out of Fruit Ninja, download and register your drop-off spot. From there pick from any business in your city (they're servicing SF, Oakland, Berkeley & South San Francisco to start), and one of 60+ couriers will be assigned to bring your goods within an hour for a dynamic, nominal fee that changes based on distance traveled, all of which you can track on your phone (sorta like Uber) and pay for with a simple credit card swipe and finger-painted onscreen signature. As for deliverables, it's pretty much anything you can think of/don't want to actually procure yourself, e.g.: all the ingredients for a first date dinner, an extra bottle of wine, two morning-after brunch huevos rancheros-es from Tipsy Pig, a pregnancy test, another pregnancy test, a book on fatherhood, tampons, a celebratory bottle of champagne, a subsequent apology card for your insensitive celebratory bottle of champagne, and another, personal, celebratory bottle of champagne
Right now this amazingness is only available on the iPhone but, in the near future, they'll be rolling out a Droid version, so, yes, you'll eventually be able to take advantage of it from Twin cell phone Towers.