The creativity of some developers never fails to astound me. Here is an application of the new APIs in Mango which never occurred to me.
Developer paradoxically named NoDo has created an app which brings a camera self-timer to Windows Phone 7. The app, which is $0.99 with a free trial, allows one to fire the camera on a delay to get in the scene or avoid camera shakes. The UI is simple, and the shot is still enabled using the camera button, which I found somewhat surprising but of course very desirable. The pictures turn up as normal in the picture hub.
The app could do with a short tutorial during the mandatory 10 second delay in the trial version, but is otherwise fully functional.
SelfTimer for Mango devices can be found in Marketplace here.