As a musician, when I hear music I tend to dissect it very carefully. I'm always trying to pick out the individual tracks, samples and patches as well as figure out what they used to create what I'm hearing. Thus, it's pretty hard for me to concentrate when I have music on at all.
John introduced me to trance while I was working for Systems on my last co-op. Specifically, I became accustomed to the "Goa" or "Psych-Trance" genres, whatever they mean. It seems goa is more "stuttery," rather, there are alot of 32nd or 16th notes constantly chirping away during a steady series of bass kicks. Granted, this isn't the music I normally listen to, but I noticed a strange thing: since the music is typically repetitive, unobtrusive, and (frankly) not all that interesting, I found myself not tuning into it. In fact, I found it to be much like auditory ritalin. For someone that finds it hard to concentrate in general, this stuff is a godsend.
A decent collection of stations is on Digitally Imported, which is also available via iTunes. I specifically zone in while listening to the Goa & Psy Trance channel. The quality isn't great (96 kbps), but it's good enough.
Try it for yourself. Thoughts?