Some password and secure note management is integrated system-wide as Keychain. Use Keychain Access to manage it.
While not as powerful as some of the other solutions, it's available on every Mac without installing anything, free, and most Mac software supports it for password storage (in fact, pretty much everything except cross-platform programs).
It's great to e.g. switch FTP clients and have the new one use the keychain entries from the previous one. I also use some encrypted file containers created using Disk Utility, and store their passwords in a separate keychain. I only ever need to remember the keychain password to open these containers and am automatically queried for it.