My favourite password manager for the Mac (there's also a Windows version but I can't vouch for it), 1Password, is now available in the Mac App Store. For a limited time it's half off - $19.99, regularly $39.99.
You'll also get a free upgrade to version 4 when it comes out later this year. Definitely worth every penny if you value your stuff online. Stop using the same password on every website and service and start using 1Password.
There's also a version of 1Password for iPhone/iPod touch for $9.99, or a version called 1Password Pro 1Password Pro for $14.99 that handles iPhone/iPod touch and iPad devices. With Dropbox syncing it makes it really easy to bring all your passwords with you - securely.