I personally own a couple of mind machines...

I have a David Paradise XL by Mind Alive (www.mindalive.ca/). I think it's a really great machine. It has quite a few programs, and is programmable or can be used manually. I use it manually to induce hypnosis in clients who ask for hypnosis work. I also use it as a meditation tool on a regular basis.

I also own a NovaDreamer from the Lucidity Institute (lucidity.com). This little toy is designed to help acheive the lucid dreaming state. I haven't used it much so far, but did get a couple of lucid dreams out of it so far. It doesn't actually create any brain state or entrain the mind. Instead, it simply makes pulsing sounds and lights in a pattern when the wearer enters rem sleep. It's worn as a mask while sleeping. Inside the dream state, the wearer hears the sounds and sees pulses of red light, and will then (hopefully) recognize this visual and auditory cue as meaning "you are dreaming."

I also toy with sound technology, and started a tribe here specifically related to that issue. See soundhealing.tribe.net

I am very interested in either building or buying a Rife/Bare machine and a Multiple Wave Oscillator. I also started a tribe to discuss these topics. See bioelectric.tribe.net