I keep a note in the safe at work providing me with sufficient hints about my password manager password to be able to recreate it - without it being something that helps anybody else (think something along the lines of "every third word of the first two stanzas of that poem my second girlfriend loved").

I have the encrypted file synced across two phones, an iPad, a work machine (including it's on-site and off-site backups) two home machines (including a Dropbox account, a Time Machine networked backup drive, and a weekly rsync of the Time Machine backup to off-site storage).

I did once leave a bag containing my laptop, and my 60G iPod containing my laptop's only backup (including my only copy of my password manager file and a fair bit of confidential work-related source code) under an outside table at a cafe right before closing time. I spent a sleepless night worried as hell about it, but a friendly and familiar waitress who kind-of knew me had found it and stashed it behind the counter with a note to her manager describing me, so I got it back the next morning. That made me a) very happy, and b) somewhat more careful and paranoid about my backup and password storage habits...