Use the Volume+ hardware key on your device as shutter button in the Camera application. You can easily activate and deactivate this feature by opening and closing the application.
Great for "photo sessions" and parties where you don't want to fiddle with the on-screen shutter button, and also for self-portraits, where hitting the on-screen button is really hard.
Web page: http://thp.io/2012/camerra/
camerra (1.5.0) harmattan; urgency=low
* Support for auto-starting the Camera UI on launch
* Support for "focus" mode (keeps button pressed for 1.5sec)
* New design of the main window / UI - dark theme
* New button to show more apps of the author in Ovi Store
* New button to launch / switch to the Camera UI manually