I was curious to see how much time I spend on my computer for 2012.
I use RescueTime to see where I spend the most time on each week. According to my RescuTime, I was productive for a total of 869h 43m. And a total of 305h 23m on distracting time. On the positive side, I did spend more time doing productive stuff on my computer than distracting ones. On the down side, that is a lot of time seating down. I know that sitting at your desk all day is really bad for your health.
For 2013 I’ll try to hit 1000 hours of actual work on my computer.
Here is a great review of RescueTime.