Oooh, this'll be fun. I won't list a ton, because I want to be able to explain how each of them has changed my outlook on music
They're more or less in chronological order.
Goo Goo Dolls- A Boy Named Goo
The first album I ever bought, when I was in 4th grade or so. They were my favorite band from then all the way until high school, when I discovered Maiden.
Green Day- Insomniac
Introduced me to punk. I literally wore out my cassette, I listened to it so much. It's still one of my favorite albums.
Metallica- Ride the Lightning
This one pretty much got me interested in metal, but there's a few other albums I listened to that also did that, like Megadeth's Cryptic Writings, but this one is the best
Dead Kennedys- Give Me Convienience Or Give Me Death
Introduced me to "real" punk. I'd never heard anything like them before, with Jello Biafra's demented and bizarre vocals and the creepy surf-guitar tone that they used. In a way, DK also influenced my fucked-up sense of humor, because I found songs like "Funland At the Beach" hilarious, with the chorus of "Crushed little kids, crushed little kids, crushed little kids adorn the boardwalk!!" and shit like that.
Minor Threat- The Complete Discography
Along with DK, they also introduced me to hardcore punk. They're more abrasive and aggressive than DK, which really appealed to me for whatever reason. It was angry, fast, and violent, and for a angsty high school kid, it was perfect.
Iron Maiden- Powerslave
This was my first Maiden album, and by getting into Maiden, that opened the floodgates to countless other bands and kinds of music. My friend gave me a copied cassette of it, and at first I only liked "Aces High," and only then because of the lyrics (I'm a military buff). After a while, though, I really started to appreciate it, and he started giving me copies of NOTB, Piece of Mind, Seventh Son, etc, and I was totally hooked. The rest, as they say, is history.
Opeth- Blackwater Park
My high school science teacher (who at one point let me borrow a shoebox full of punk CDs, including the aforementioned DK and Minor Threat albums, and also was the one who got me into Maiden) mailed a burned copy of this to me one day, saying that I should check it out. I'd never heard vocals more extreme than, say, Slipknot to this point, so it really threw me for a loop. However, I didn't dismiss it or even dislike it. I enjoyed the musicianship, and eventually got used to the vocals. I credit this album with introducing me to extreme/death vocals and basically all of extreme metal.
The Clash- London Calling
London Calling is now my favorite album of all time. I bought it on a sheer whim; the only Clash songs I'd ever heard were Rock the Casbah and Should I Stay or Should I Go, neither of which are on this album. But I was blown away by the diversity of styles: Reggae, rock, punk, jazz, pretty much anything you can think of. No two songs sound alike.
Sleater-Kinney- The Woods
And now we come to the most recent of my "life changing" albums. Two summers ago, I read a Rolling Stone review of this album (it had just come out). I'd heard one of their songs on an anti-Bush compliation I had, and I liked it, but I didn't really give it a second thought. After reading the review, I decided to download The Woods and check it out. I wasn't prepared for the avalanche of howling feedback, thundering drums, or Corin Tucker's earth-shattering wail. It was one of the only albums I've ever heard that made me just sit back and go "Whoa. What the fuck was that
??" Needless to say, they instantly became one of the my favorite bands ever.
So there you have it, my musical history