I have to adopt this:

1. Avoid using instant messaging: It’s a constant source of distraction.
2. Only check your e-mail twice a day: The surest way to waste time is the ol’ Send and Receive button.
3. Stick to what matters: Take care of the most important stuff first. Don’t waste time on low-priority stuff. (In fact, delete the low priority stuff from your to-do list. It’s not going to get done anyway!).
4. Ask for alone time: If you need uninterrupted time to get something done, politely notify your co-workers that you’ll be unavailable for a couple of hours.
5. Limit blog-reading time: Set a time limit on your blog reading. If you don’t get through all your blogs in that amount of time, hit the trusty “Mark All As Read” button and move on.
6. Make lists: Write a “to do” list for each day (on paper if you can bear to tear yourself away from Outlook). Put the time-sensitive stuff at the top and be realistic. Choose three time-intensive things to do and five quick things to do. Make sure you finish all of them before you leave in the evening.
7. Restrict meetings: If you can, restrict the amount of meetings you call, or are involved in. Meetings drag on and can eat into your day. Instead aim for one or two meetings per week and plan them carefully to ensure you cover all important topics and keep on track.

Tips 1,2,3 and 6 are the way to go, sometimes you’re really focused on something and someone bugs on IM, you change your window, lose your focus and context, and when you return you waste precious minutes of your time figuring out what you were doing.
Checking mail only twice a day is a great tip also, how many times did you stop working to check out that stupid video a friend sent you, Outlook it to blame, with the new mail notices, I’m turning that off.
Sticking to what it matters is also very important, I don’t know how many hours I’ve spent trying to place that page exactly how it was supposed to be, when the main functionality is yet to be implemented.
I’ve found that the “getting things done” philosophy really helps, if the tasks takes less than 2 minutes to be done, do it right away, if not, note it down, when you come um with an idea, write it down, chances are. you’re gonna forget about it 3 minutes later.

(list stolen from here)