Sony eMarker

Back in the year 2000, Sony introduced a nifty little gadget - a keychain priced at $20, which enabled you to easily tag your favorite songs while listening to the radio. All you had to do was hook it up to your computer and it would automatically launch a program. This program would then cross-reference the timestamps of your tagged songs with the list of radio stations that you had selected as favorites in your area. In just a few clicks, you could know exactly what was playing on the radio at any given moment.