I listen to Spinner.com while I program.
Channels - Jungle/D & B or Gothic. Its great if you have a cable/DSL/edu dorm connection. No fiddling with CDs. It even has a Techno channel.

Occasionally I wander to PerlMonks to look through where I can chirp in with my opinion or advice on things that I know or have knowlege of. Or even to ask a question or two. It's not a bad thing to do realy as long as you don't let it sidetrack you too long.

If you find yourself not being able to concentrate at all no matter what you do. You might need a break. Especialy if you have been at it for over an hour or so. Step away from the comp and get some air. There is such a thing as too much. When I start feeling like that. I do take a break for 10-20 minutes or so and when I come back to the comp I find I can concentrate better. If its late at night (like after 2am or whatever your usual limit is) and even after a break you feel as though you still can't concentrate it might be time to hang it up for the day if you can. Better to be fresh than to make a huge amount of mistakes only to waste time to correct them later.

BMaximus