Yes, there are HDTV signals floating through the air, and you don't have to pay for satellite or cable to receive them with the Spectrum LP49-DTV indoor digital TV antenna. The company says the antenna can be used anywhere the UHF standard is supported, and can receive digital or HDTV signals and feed them into a set-top box or DTV-ready TV.
It won't pick up HBO, but for network TV, it might be able to do the trick. It was not mentioned why this device is better than good old rabbit ears, but it sure as hell looks cool.
Watch HDTV for free with an indoor antenna [Aving.net]