Working from home: tips on setting up your environment
altdevblogaday.org
altdevblogaday.org
Do X for 3 years, then give advice to others on how to do it.
It really helps my concentration and productivity.
A trip to the office for a couple hours a week or meeting up for lunch with a coworker has the effect of keeping me focused and interested in the work at hand.
I also feel like chatting in IRC with my coworkers helps a lot.