Two albums that changed my life are Beastie Boys Ill Communication and White Stripes De Stijl.
The first one I suppose is rather embarrassing now, especially since I haven't listened to it in years (I'm assuming I would still enjoy it, I know I still really like Ricky's Theme and Transitions), but when it came out I was obsessed with it. I started reading everything about Beastie Boys I could including their own Grand Royal magazine.
This in turn got me into Sonic Youth which opened an enormous musical vein that led to other indie/underground music like Pavement, Smog, Sebadoh, Palace, Superchunk as well as older or more avant garde artists like Velvet Underground, Patti Smith, Television, Boredoms, Can.
Ill Communication next got me into punk rock like Bikini Kill, Huggy Bear, Buzzcocks, Bad Brains, Minor Threat and Fugazi. At first it was whatever they name dropped but then like anything else once you get into it you start investigating and exploring.
Next it turned me onto jazz and funk and I got into Sly and the Family Stone, Lonnie Smith, Eddie Harris, Miles Davis, James Brown. Just like punk I started exploring these genres.
Lastly it got me into hip hop, which I had a very basic understanding of at the time, I think I owned some Public Enemy and Run DMC and whatever else was pretty big but it got me into a Tribe Called Quest which led to all that late 80's early 90's hip hop, De La Soul, Wu Tang, Jungle Brothers, Aceyalone and Abstract Rude and then it was more exploring.
As far as the White Stripes De Stijl album, I never had much desire to listen to the blues, I think I had a fixed notion of what they were and so didn't even give it a chance, but listening to the son house cover and then getting into Son House and Robert Johnson, Skip James, Mississippi John Hurt, and way too many to list, I now feel like that form of music is probably my favorite ever created and can't really imagine not listening to it. It's so pure and raw and for recordings that are 70 years old they feel so alive.
There are other albums which have changed my life, but no two albums have had such a dramatic impact.