Get one of those timers you use for cooking or even a stop watch. Set 1 hour on it and then do nothing but one task. Shut off your phone / icq etc. Also at work I have installed a firewall that blocks gfy, yahoo finance etc. Use
http://www.rescuetime.com/ to tell how much time you are wasting.
Yoga / Meditation also help which I do these days. The key thing is not to have a "moneky mind" (not hop from one task to another every 2 min)