Don't worry - the "Applications" folder is provided only for convenience. There's nothing special about it. You can have all your applications installed in a single directory in /Users/<yourlogin> or /Users/Shared or anywhere else. Applications will work well regardless of where you have copied them into (if you scroll through /Applications, you'll see that some applications actually create a directory within /Applications - even the default installation of Mac OS X creates a "Utilities" directory within /Applications).
Mac OS X knows an application when it sees one (and will show the application icon) - doesn't matter where on the system it's located (could even be an external drive). As long as you provide the required access to the directories that contain applications (and to the applications too) to other users, they will be able to use them.