Dr. Robert Bussard, best known in the sf world as inventor of the Bussard ramjet, has spent the past 15+ years working on building a cheap, safe fusion reactor. He spoke at Google last week about the project, and the video of his talk is now available on Google Video.
His proposed process "converts hydrogen and boron directly into electricity producing helium as the only waste product" (to quote the video description). His talk was fast-paced and highly technical; I didn't understand more than a tenth of the technical details, and anyone who's not a physicist or an engineer may want to skip a lot of the technical parts. But even if you do skip most of it, it's worth watching the introduction and the less-technical parts, and the cool photos of the prototype machines.
If you don't have time to watch the (90-minute-long) video, there's a posting from June at randi.org (written by Bussard, posted by someone else) that provides a brief summary of what happened.
Bussard's group had what appeared to be a huge breakthrough late in 2005, literally days before they had to shut down the lab because their funding had run out. Their prototype more or less self-destructed in the final test.
Bussard now says he needs about $150M-$200M to turn this into viable technology. Part of his talk is an extended utopian discussion of what effects cheap energy would have on society; that segment starts around 1:01:30 in the video and runs to around 1:06:30. (It's pretty much what you would expect, but it's fun to watch his enthusiasm and, yeah, hyperbole.)
I certainly can't judge the science here on its merits, but I found the talk fascinating.