When your iTunes playlist starts sounding old and tired, when the newest videos on MTV have lost their shine, or when you've heard the new Britney Spears song on the radio for the fifth time this hour, dust off your CD collection (or your parents') and pop one of these classics in:The Beatles, "Abbey Road"
The last album the Beatles recorded, but not the last one released (not that "Let It Be" really counts, anyway), "Abbey Road" was the beginning of a rock album as a rock album, not a collection of songs. From the shimmering "Come Together" to the heavy and growling "I Want You (She's So Heavy)" to the inspiring proclaimation of "The End," "Abbey Road" is the final masterpiece of the greatest band in rock 'n' roll. It was one last hurrah for a band who loved each other, loved their fans and, most importantly, loved their music.
Key Tracks: The medley starting with "Because" up until the final ditty of "Your Majesty."

Bob Marley, "Legend"
Maybe it's a cop-out to recommend a greatest hits album, but there's nothing better than over an hour of the best music Bob Marley ever made. Starting with "Is This Love," ending with "Jammin'" and squeezing classics like "Buffalo Soldiers" and "Redemption Song" in between, this album simply does not miss.
Key Tracks: All of it.

Pink Floyd, "Dark Side of the Moon"
It is a challenge to name the individual songs on this Pink Floyd classic because they did such an amazing job making the entire record flow as one. With repeating themes of a heartbeat opening and closing the album, manic and insane laughter on "Brain Damage," incessant dark humor and cultural critique ("Money"), "Dark Side of the Moon" is both an ode to lost vocalist Syd Barrett - who went insane - and a scathing review of the world. Roger Waters displays his best songwriting, both musically and lyrically, on this album, which hovers at the apex of Pink Floyd's career.
Key Tracks: All of it.

Derek and the Dominos, "Layla and Other Assorted Love Songs"
This is nothing short of Eric Clapton at his musical and lyrical best. Recorded during a period where Clapton fell for and pursued close friend George Harrison's wife, "Layla and Other Assorted Love Songs" contains quite possibly the best blues songs written in the second half of the 20th century.
Key Tracks: "I Looked Away," "Bell Bottom Blues," and "Layla."

Led Zeppelin, "IV"
This album is more than "Stairway to Heaven." It just happens to be every Zeppelin song you've ever gone gaga over.
Key Tracks: "Black Dog," "Rock and Roll," "Stairway to Heaven," "Misty Mountain Hop," and "Battle of Evermore.