Below is a great web tool to see just where on the screen you are tapping for touch screen devices like the Raspberry Pi single board PC. I needed to rotate my display 90* along with the touch interface so I had to find the right combination of x-y invertion settings to get it right. This is mostly for me in the future and anyone else who might find it useful.
~ConsultingJoe
http://scripty2.com/demos/touch/touchspector/