I've written a gem that cross references your computer activity auto-logged with TimeSink ( http://manytricks.com/timesink/ ) with your git commits, and generates a line item pdf invoice.

https://github.com/aantix/big_bucks_no_whammies

Here's a sample invoice : https://github.com/aantix/big_bucks_no_whammies/blob/master/...