My main distraction is noise, since I mostly work from home, and my home can be a rather noisy place sometimes (I don't live alone). The sound of the TV, for instance, can be anywhere from a nice background presence (like for a documentary) to an impossibility to work (like an action movie that tries very hard to catch your attention).

But one day, I tried this, and boy did it change my life! http://simplynoise.com/

I'm pretty sure this doesn't work for everyone and can get annoying to some people; but for me it was a revelation and solved a problem for good.