App offers lots of features such as customizations: head size, head alignment, silent mode, full call control: accept/deny, mute, toggle speaker and end call.
If you don't want to turn the app on for all apps, there's a chooser for what apps the CallPop-up will work.
This app is very light-weight, contains less than 550kb of whole data. It comes in pretty holo interface and it's very easy to use.
App works on every Android phone running version 2.2 and higher.