Now we have MacOS 9 with its great new features, and a keychain to be sure we won't forget any password. But there's one caveat: we still have to know the password to unlock the keychain!
Use the Unlock Keychain Applescript-model to create your own keychain-unlocker! No fancy tools needed.
If you want to unlock more keychains you can duplicate the line before 'quit' in the script as often as you want, filling in different keychain names and passwords.
SECURITY ISSUE: It is possible for people to read your password in the run-only Applescript you create with this model. Make sure no-one is able to access your script over the network. If you don't know who has access to your computer you should consider using the Multiple user accounts of MacOS 9, or the Password Security for powerbooks.