Cool discussion. I'll definitely give the music a try.

I listen to a bit of psychadelic rock music it is a remarkably powerful tool at achieving a state of mind that is conducive with lucid dreaming - I mostly listen to Tool and Pink Floyd at the moment. Tool achieve this dream-like quality by using very obscure time signatures, and cross-rhythms. While you listen to it, close your eyes and relax. Breathe regularly and just feel the music. Let it flow through your mind. You'll probably get the hypnagogic (not sure about spelling) imagery appearing and then the fun happens.

My favourite tracks for this are:

Tool - Third Eye
Tool - Lateralus
Tool - The Patient
Pink Floyd - Dogs
Pink Floyd - Pigs
Pink Floyd - Dark Side Of The Moon album
Led Zeppelin - No Quarter
Beatles - Across The Universe