Albums that I'll never put away for good no matter how my tastes change would definately be Jeff Buckley's "Grace", some of Oasis's albums (Standing on the Shoulders of Giants, The Masterplan, What's the Story), The Verve (Storm in Heaven)... I've gone through big phases of liking Blues records, different types of Brit rock (Ocean Color Scene, Stereophonics, JJ72, Placebo, Starsailor, Muse etc...), "classic" rock (GnR, The Who, the Pistols etc...) and Hiphop/rap (JayZ, Kanye, Nas, Gangstarr, The Streets, 50...). While I keep actively listening to all of them, sometimes some of them take a major backseat... haven't listened to any of my GnR records in ages. Used to be the biggest fan.
Then I have a pretty huge classical collection, most notably a fairly extensive collection of violin repertoire. No matter how many different soloists I listen to, with new and fresh ideas about how works should be performed, I'm always drawn back to the good old playing of Itzhak Perlman. There are some records which I think define your personality and what inspires you that no matter what changes you go through, you're fundamentally hooked on for life.