One of the coolest features of Photoshop for iOS is the "Scribble Select" tool. You draw a fat green line around any object you want to keep, and scribble some red into the parts you want to delete. Hit "OK" and a few moments later you have your subject, neatly cut out from the background, better than you could have managed on even the best desktop machine of a few years back.
But what if you aren’t near your iPhone or iPad when you need to do some quick ‘shipping? You need the browser-based Clipping Magic.
It works just like the Scribble Select tool, although without some of the more advanced features. Right now (the web-app is in alpha) you’re stuck with whatever the app gives you: there’s no way to refine your edges. But the "magic" works fine inside the browser, and if all you want is a quick-and-dirty background removal then you’re good. The edits are even applied as an Alpha transparency channel, which means that non-destructive finessing could be coming sin the future.
Once done, you can either download the file or share a link to save you downloading. Not that that should be a problem – Clipping Magic is currently limited to non-iOS browsers, so you’ll probably be hooked up to a fat internet pipe anyway.
Go try it. It’s free. And if you’re using an iPad? Grab Photoshop! It’s way better, and almost as cheap.