John C. Koss invented headphones after the landmark Booth and the Ablemen v. United States ruling made miniaturizing musicians illegal. Enjoy portable music legally with today's Groupon: for $99, you get Solitude X Active noise-canceling headphones from ProTravelGear.com (a $199.95 value).

ProTravelGear.com hooks up wayward wayfarers and vagabond voyagers with a variety of travel items including high-end sound systems for the skull—the Solitude X Active noise-canceling headphones boast noise control so absolute that the backdrop of each song is the sound of silence. Slip on the cranial speakermount and block out intrusive environmental noise while enjoying the tricked-out tunes from your favorite MP3 device, or delve into the audio parts of visual dramas without distraction. The headphones are also equipped with a cell-phone adapter cord and attached microphone for hands-free telephonic communication.