I memorize about a dozen or so of my own personal passwords (mainframes, unix servers, novell, lotus notes, newegg, anandtech, oracle databases, and more) as well as 20 or so of the different account passwords that I or my coworkers use on a regular basis at work.
Due to some passwords expiring after 30 days, some after 42, some after 60, some after 90, and others after 180, and the fact that I have so many frickin logins, there is no hope of keeping passwords consistent. Also, some require alpha numeric, some only numeric, some only alpha, some require symbols, some won't accept symbols, and the list goes on. Ohh also some need to be 8 or more characters, and some only 4 or 6.
For the other 100+ other passwords that everyone on my team at work has access to, we use
http://passwordsafe.sourceforge.net/