I thought I'd throw out this link to a recent news article:
http://www.wapd.org/bbs/msgs/9499.html
A Japanese toy company announced a product that might help people choose what they dream about. Basically, you record some keywords into it and put a picture on the front of it. Along with some music and a "special" white light, it uses simple timing so that the keywords are repeated back (hopefully during a REM cycle). They claim a 22% success rate.
My thought is this: If simple timing works a little, then why not attach a heart or brainwave monitor in order to perfect the timing. Has anyone heard of a more robust approach to this with a better success rate ?