The winners of the Greener Gadgets Design Competition have been posted on the web, including the Grand Prize winning Enerjar, the "do-it-yourself power meter." There are several smart, interesting designs, but the Enerjar really does look great, with plans and software to be distributed freely on the web. (Now I just need somebody to build a one-click parts pack for order so I can build one myself without having to source all the individual items. Hint.)
Winners Page [Core77.com]
Update 03/03/08: The designers of the Enerjar have now put build instructions online.