Data Guardian 2.0

Data Guardian is a password database app for Mac OS X. It allows you to store your passwords and web logins in a secure database.

I was unable to find a way to password-protect the application during my time with it, but there is a mention to it on the website. Maybe the trial version can't use this feature or I just didn't find it.

You can create as many entries as you want with your passwords and logins. These are saved for you and you can customize the information that you want to save for each entry. For example, when you add or edit an entry, the available fields are Name, Login, Password, URL, and Notes, but you can add new fields, and you can name them whatever you want. You only have to specify what kind of fields they are, like text, e-mail address, etc. Typing in information is easy enough and you can click the copy buttons to make the process easier when creating multiple entries.

As I mentioned, I wasn't able to access any sort of password protection. From the preferences menu, there are a few security and privacy options, though. These allow you to configure the app to clear the clipboard at regular intervals, or carry out actions when the application is inactive.