The Swiss Institute for Applied Environmental Technology (UMTEC) has published a great “checklist for identifying dubious technologies“. Following the advice given in the document can help you avoid wasting money on the many fraudulent miracle inventions out there. They also have a number of other publications available for download although most are not in english.
Tip of the hat to James Randi for pointing this out in his newsletter a couple weeks ago.
Paul Hutchinson's Blog 