I was looking for beacon circuits, and ran across VK3YE’s USB powered 40m transmitter. Unlike most simple beacon transmitters, this one transmits double sideband, which makes voice transmission possible. I like the basic idea!

USB port powered 40 metre milliwatt transmitter on air – YouTube

Very cool. He’s also got an awesome awesome YouTube channel, with over 180 vids uploaded. Lots of good information on crystal radios, homebrew, and low power operation. Snoop around! I was particularly intrigued by this video showing low power SSTV operation: