I try to maintain good password practices -- total random gibberish, never use the same password for two things, change them monthly --, and the EBP lite from http://mandylionlabs.com/ certainly helps.
Last night, at about 3am I was doing my monthly password change and somehow I typed one password wrong in exactly the same way three times. Today when I tried to add my ssh private key it just wouldn't unlock. I tried the "right" password 10 or so times and no luck. I then started trying slight variants on the password: fingers shifted, missed shift key, similar looking characters, etc. After 30 or so of those tries with no luck it was time to script.