I just found a cool new app (only for iphones sorry android!) that you use for measuring your putting. It clips onto the shaft of your putter and it measures the tempo, face angle and arc angle of your putting stroke. You can do a test and it even gives you a putting handicap showing how consistent you are. The app is free but you have to pay $30 to get the cradle that attaches to your putter shaft. Pretty cool I reckon.
The app was released in the last day or 2 and I downloaded it before to try. I just taped my phone to putter and it was a bit loose so I am not sure on the accuracy of the measurements but I had a few tries and it seems to work fine. Here is a photo of some of the info you can get off it.