I HIGHLY recommend BrainWave Generator. I can come home from a stressful day, flip on the headphones, and instantly relax ("Surf" is just awesome). Nothing irritates me when I'm listening to the tones.
There are people who have suffered from chronic insomnia, have tried synthetic and natural drugs to no avail, but have gotten profound results from this program.
What's nice too is that you can create your own presets, or even download others' as well. You can make your own background sounds and associate them with the presets (one guy uploaded a WAV file of a didgeridoo...way cool!).
There is anything from stress relief, headache relief, depression allayment, sleep induction, to OBE induction. There are some awesome presets that do things to you that you never thought possible with sound. It's almost like being in one of those sensory deprivation chambers.
The program is actually free (it has basic built-in presets), but you can't download/upload anything unless you purchase it ($40). Way worth the money, though.
The world goes away, if only for a day.*
*I have no affiliation with this organization whatsoever.
Magis Amica Veritas
I would rather control myself, than someone else.
en courage (heart)
in spire (spirit)
en thuse (theos)