Grass is Greener (GIG) technologies promise you everything tomorrow for a hamburger today. Daydreaming about their Neato Factor is fine but these hope technologies become cuss-worthy bad when they steal stage from true talent.
The List (I'll add to this as I come across appropriately screwy examples. Eventually I'd like to break these down into categories.)
High Altitude Wind
Solar Space Power
Super-conductive Transmission Lines