I read an article from Microsoft advocating passphrases in 2004, and was taken with his rationale. I've been using them since then on everything except low-security accounts.

I now have much more diversity in the hundred or so passwords I actually use than I used to, and worry much less about forgetting them.

(P.S. Without loss of generality, pretend that for whatever reason I was reminded of Gummy Bears when signing up for my Gmail account. (An American TV show from back in the day.) I take a snippet of one line from their themesong, "dashinganddaring", which works fine as a password, optionally substituting a & for the "and" and with arbitrary capitalization. I'm highly unlikely to forget the password because, well, I've had perfect recall of that themesong for twenty years now.

I don't actually use cartoon theme songs, but everybody should have some source of highly entropic data that is evocative and meaningful to them.