UK Company Triggertrap have been making camera triggers for some time now, and recently released an iOS app that offers remote control of many DSLRs, in addition to control the iOS camera itself. Unlike other remote apps available though, the Triggertrap Mobile can be triggered by things like sound, vibration, and facial recognition. Other notable features include eased timelapses that create a ramped-up speed effect over time, distance-lapses, and doing HDR captures.
The $10 app will control the camera built into your mobile device, and is available in the app store. There is also a free trial version available which gives you access to just a couple of the shooting modes. (cable release mode, vibration sensor and timelapse mode) It will work on any iOS 5 device, like the iPhone or iPad.
You should note that if you want to connect it to your DSLR, you will also need to buy a $10 cable AND a $10 dongle to connect everything. Too bad it doesn't work on a self-generated wireless network, but it's still a cool product for an amazing price when you consider that a Canon Timer Remote control is over $100, and it doesn't do nearly as many of the funcitons. Check their site for specifics regarding camera model compatibility, but some of the more popular Canon and Nikon DSLRs I looked for seemed to be supported, including the 5Dm2, 7D, D3, and D800.