Passwords
Remebering passwords is a chore, its becoming more important with the ready increase in cracking power. I can just see some windows worm being designed right now to provide more distributed horse-power to crack passwords and distributed disk space to create massive password dictionaries. Combined with a little more cunning, these beasts are going to start automatically cracking passwords on systems they compromise.
There was a recent discussion on debian-user with some clever ideas for generating passwords.
Personally I agree with Karsten M. Self. Eventually the best way to secure our systems is going to be with tokens.