Keepass is an excellent password manager which is free, open-source and available for all the platforms (for Mac and Linux, KeepassX is available)

Roboform for Windows is a robust password manager which also helps you easily fill web forms.

Firefox's in-built password manager could be a good option too for managing your web passwords.

Sxipper is an awesome Firefox extension which helps you to fill in forms, manage passwords and Open IDs.

LastPass has recently added some cool features and could well become the most popular password manager out there.

Like LastPass, Clipperz is also an online password manager which not only stores passwords but also information like bank account numbers and credit card numbers.

Password Hasher is a nice Firefox extension whose main task is to create strong passwords for you.

1Password is not free but works very well for Mac users and hence it is quite popular.