How to get a complete list of all applications installed?

Solution 1:

Try: About This Mac > More Info > System Report > Software

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Not only "Installations" ... but the others may give you some info, too.

Solution 2:

If you're just looking for a list of applications with a .app extension then starting the Terminal and running

   find / -iname *.app > ~/applications.txt

will (eventually) give you a pretty comprehensive list of applications, written to a text file called "applications.txt" in your Home folder.