Update
Thanks pbjabba for the comment:
Available for $29 when using the HN promo link: http://brain.fm/HN
Original Post
It's generated music which is supposed to help you focus, relax or sleep.
I've been cycling through free trials for months at work, struggling to justify the original price, then I saw this link in a comment on hackernews.
I find that if I use the 'focus' music, I'm "in the zone" within minutes.
I got prompted to get a further 10% off by registering an email address with the digg store, making it USD$35.
If you want to try it out, you can sign up with anything formatted like an email address (they don't verify) at http://brain.fm and try the 7 free sessions
US$39 Lifetime subscription
US$29 3 year subscriptioon
US$19 1 year subscription
P.S. This is my first post here.
Might be useful to place in there that it's meditation/relaxation/productivity music. I had no idea what this service was.