I reckon last time I lost mine was a filesystem corruption (after a hard lockup), not sure how I'm going to put out that fire?
Backups on a different drive. Having an SQLite database in your home directory isn't really going to help you there (I mean as far as: if only parts of the filesystem are corrupt and you have re-duplicate entries, your chances are better of finding a working one - but it's hard to call that a solution).