Suggestions
WhatPulse
As a developer, my productivity is largely quantifiable by the number of keystrokes (and mouse clicks) I produce during a day. I’ve been tracking this data (and a lot of other data that could be useful) with WhatPulse.
WhatPulse provides an unauthenticated Web API (because the stats are public), which should make it fairly easy to track pulses. See http://whatpulse.org/pages/webapi/ for more details.