How to create drag-and-drop installer for MacOS X?

Question

What tools are used to create installers like this:

EDIT: Here's a full tutorial: http://chromasoft.blogspot.com/2010/02/building-dmg-installer-for-mac-simple.html

Answer 1

It's just a folder with a custom background image (right click on the folder background and select "Show View Options"; Firefox also sets a larger icon size and adjusts the grid to match, also in the same place). The link to /Applications is created by Control-dragging. Once you have the original folder set up, you can use hdiutil to create a DMG disk image from the folder.