How can I ensure only "whitelisted" applications run on OS X There is a security technique called whitelisting (available in Windows 7) that ensures that only specific applications and processes will run.

This is different from email whitelisting and only applies to applications running on an OS.

How can I implement whitelisting (apps) on OS X?

For example, I generally want to constrain apps to those allowed by the setting "Mac App Store and identified developers", but I would also like to run the IM app called Spark.  OS X refuses to run that app with this setting and reports that the app is "damaged".  I can change the setting to "Anywhere" and that will allow Spark to run.  The problem is that will also allow all apps to run, some of which I might regret.
You can do this using the Allowed Apps settings in the Parental Controls System Preferences Control Panel: