Why not use Enterprise Manager and store the SYS password as a preferred credential. That way you only need to remember the password to Enterprise Manager and the rest is sorted for you.
Alternatively, use a standard pattern in the password but prefix/suffix it with the SID/Database Name. That way all the passwords are different, but easy to remember.
Obviously, if someone founds out your pattern they have access to all your machines :(
Alternatively, set them all to "password" no-one will ever thing of that!
Cheers
Tim...