The Clash: London Calling
Is there even any reason to explain why this one is here? The Clash was/is one of the best bands (punk or otherwise) ever, and London Calling is pretty much a perfect album (double album, no less!). Nobody mixed punk, rock, pop, and reggae so effortlessly with such amazing results. Plus it's got a cool cover that plays off an early Elvis record.
If you don't think the Beatles are one of the best and most influential bands ever, then you're just wrong. Revolver which sounds as good today as I'm sure it did when it came out 35 years ago is my personal favorite (I'm not alone on that opinion), with a good mix of guitars ("Taxman"), strings ("Eleanor Rigby"), horns ("Got To Get You Into My Life"), cheese ("Yellow Submarine"), and ahead-of-their-time experimentation ("Tomorrow Never Knows").
I'm a huge fan of the emo "rock punk" genre: bands like Jawbreaker, Hot Snakes, Knapsack, and Seaweed. Samiam is one of the originators of this, with fast, powerful guitars that just sound better the louder it's played. This is one of those albums that I don't know the names of any songs, yet I know every song by heart. Soar is my favorite Samiam CD, and with good reason: there's not a bad track here, and there's even one song with lyrics by Ed Grimley top that!
Elvis Costello & The Attractions: This Year's Model
Elvis Costello is a great songwriter, and This Year's Model is easily one of his (if not the) best albums. The songs are so good lyrically, and The Attractions' sound (his first album with them) blend perfectly with Elvis' distinctive voice. In addition to my favorite Elvis song, "(I Don't Want to Go to) Chelsea", you'll also find several of his classics here as well ("No Action", "Pump It Up", and "Radio, Radio").
Public Enemy: Fear of a Black Planet
Yes, I know that It Takes a Nation of Millions to Hold Us Back is the better album Millions was groundbreaking and raw while Fear "merely" continued the bring-the-noise sound, which was more polished. But it's still an amazing CD with classics like "Fight the Power", "Welcome to the Terrordome" and "Brothers Gonna Work It Out"; not to mention underappreciated cuts like "War at 33 1/3" and "B Side Wins Again".
Bad Religion: Suffer
One of the leaders of the 80's punk revival, Suffer is the Bad Religion album that solidified their sound. Fast, smart, catchy, and short 15 songs (and not a bad one among them) in 26 minutes! all later Bad Religion CDs (the best ones, anyway) followed Suffer's formula.
Hepcat: Right On Time
I like ska, but really good ska albums are difficult to find they usually have a couple good songs surrounded by lifeless filler. Hepcat, however, was able to release a near-perfect album. Heavily influenced by 60's traditional ska, rocksteady, and reggae, Right On Time is the extremely rare ska CD with no throwaways nothing but great catchy songs.
Built to Spill: Keep It Like a Secret
Built to Spill's sound is tough to describe it's most often described as a kind of indie rock Neil Young. I was introduced to Built to Spill via There's Nothing Wrong With Love, a fantastic album. Keep It Like a Secret rocks a bit more (I'm sure due in part from major label backing) and is catchy as hell, and has now become an essential part of my CD collection.