I have posted a Lucid Dreaming sound file I got from a Brainwave Generator Preset that someone posted in another place. It is 30 minutes, and I faded in and faded out the first and last 20 seconds.

It uses binarual beats to aid in relaxation. You may want to listen to it at a low volume level.

It drops to 3.5Hz after 15 minutes with a 2nd frequency dropping to 2 Hz after 15 minutes. It stays like that until 30 minutes, where it fades out over the last 20 seconds.

http://www.cnetworksllc.com/mp3/BWGenLucidDreaming.mp3

It is about 30 Megs, and pretty relaxing. I use a 90 minute version myself, which is too big to post here.