For simple passwords and encrypted notes, the Mac OS X Keychain would work, or 1Password would be a great option.
For something that could store lots of things (e.g. PDFs of your bank statements, and all manner of private documents), consider EagleFiler. it can create an encrypted library, and it uses the Mac OS X feature of encrypted disk images to wrap the whole thing in an AES 128 or AES 256-encrypted image. It would be great for something of this nature.