Ok, this is kind of embarassing... About nine years ago, it seems that I PGP-encrypted some of my archived mail files (maybe because the files were on computers at work? I don't remember doing it, let alone why.) Anyway, I can't remember the passphrase, and it's not in /usr/dict/words. Chances are I picked a moderately-good password, and possibly even a long one.

What tool should I use to brute-force it?

I found a program called "pgpcrack" by Mark Miller, but it wants to be given a list of every passphrase to try. I think I need something more brutish than that.