The most productive way to work to just concentrate on one thing and do it, Multi-tasking makes you fill efficient (look at how many things I'm doing in the same time) but it's a productivity killer – you spend a little bit of time re-orienting yourself every time you switch tasks, and that time adds up - you could get things done faster if you did them sequentially.
Also, in today’s connected world, when you’re flooded with e-mail, phone calls and instant messages in addition to the traditional co-worker or boss stopping by and breaking your concentration it’s a wonder anyone...