Here's some great news: You may already own an HDTV and not know it. If you have a computer with a display that supports 1,280-by-768-pixel resolution or higher, you can watch high-definition programming. Here's how: HDTV content from the major networks (ABC, CBS, FOX, NBC, PBS, and more) is broadcast free of charge over the air. The HDHomeRun lets you harness this programming, and the Elgato Eyetv 3 software for Mac can convert TV recordings into formats you can watch on a variety of devices. This interesting gizmo grabs broadcast HDTV signals, pipes them to your Mac or PC, and comes with the software you need to record, view, and share programming.