I use
Genpass for a number of web passwords (not my banking password). You give it a master password, which it hashes and mixes with a hash of the domain, so it creates strong, different passwords for every website that you visit. It works as java bookmarklet, and is very convenient.
For ssh, I use
keychain so I don't need to keep decrypting my private key everytime I ssh into other systems using key-based authentication. I decrypt the password when I login, and it is stored encrypted in memory. Very convenient and as secure, for all intents and purposes, as typing it in each and every time. Just remember to logout when you leave your desk.
I use the KDE Wallet daemon to keep e-mail passwords for KMail and IM passwords for Kopete encrypted.
In my opinion the security benefits of using a password manager for at least some of your passwords outweigh the risks significantly. It allows you to use longer, stronger passwords and most of all discourages lazy reuse of passwords. I also keep every password & username I have on a pair of small pieces of paper.
For the curious, the heuristic I use to generate memorable passwords is to take a long phrase and use the first letter of every word combined with some substitutions (> for 'in', etc) and changes in capitalization.