It previews the grab and allows you to mouse around and read actual Android coordinates.
You can also click on things and the Android gets the clicks.
It also supports various navigation keys.
Because it has to grab frames over ADB it's not spectacularly fast.
If you have a device with a broken screen it could be very useful.
This is a work in progress with features coming.
It uses a mixed command line/GUI interface.
Download in the signature.