Sure enough, just after I'd settled on a top 5 list for 2006, I discover great albums I missed (I knew about them, but hadn't got round to buying them until the prices came down):
1. Tom Waits, Orphans: Brawlers, Bawlers & Bastards
OK, so I haven't heard the last of the 3 discs that make up this retrospective collection of b-sides and unreleased material, but the first disc ("Brawlers"), alone, is among the best things released in 2006. The second disc ("Bawlers") is also very strong. This is a nice break from more recent Waits releases, which are a bit too filled with noise for me. If you miss the "Rain Dogs" era Tom Waits, go buy this set. Now. (Also available as high quality MP3s from eMusic.)
2. Brian Eno & David Byrne, My Life in the Bush of Ghosts
This is a reissue of the album originally recorded in 1979 (before the Talking Heads' fantastic "Remain in Light"). It's a largely instrumental work combining found sounds, percussion, guitar, and electronic effects. Listening to it now, I'm completely stunned -- much of the best of contemporary electronica was clearly birthed by Eno in 1979. Essential history, but also great music. And the SF Public Library has a copy, which I just returned, so you can borrow it next!
3. Tori Amos, A Piano: The Collection
This is clearly aimed at fans who already have all the albums, and there is no way I'd pay retail for it ($75), but now that it's available through the record clubs (YourMusic.com for ~$33 shipped), I sprang for it. It's reminded me why Tori is my favorite artist. By focusing on the earlier material (the entire first record is in here), as well as a few alternate mixes and essential b-sides, this 5 disc "box set" delivers the very best Tori has put out over her 15 year career.
4. Richard Buckner, Meadow
Richard Buckner has a Tom Waits kind of vibe -- equally dark, a bit more country, more guitar focused. His earlier records, "Bloomed" and "Since" are essential. This album takes him back toward those albums -- cleaner production, discernible words. Available on eMusic (try two songs -- "Town" and "Spell" if you want to be convinced.)