Apple - Can I get the original Mac font Chicago on a Mountain Lion Mac?

The last version of the OS to use this font as default was System 7.

For Mac OS 8, Apple decided to discard this wonderful part of their brand’s identity, and commissioned David Berlow of the Font Bureau to design Charcoal.

Apple actually released System 7 for free download here. Conceivably you could load up System 7 in an emulator like Sheepshaver and get the font out somehow. Or unpack the system images provided by Apple, though I don't know which software you would need for that.

Apple abandoned Chicago as of OSX, as evidenced by the outrage here. Locally, I can buy an original iMac running OS 9 for 50 EUR. So you could buy one of those and transfer the font :-)

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UPDATE: extracting Chicago from System 7

1. Download the System 7 disk image from Apple for free here
2. Unpack System 7.0.1.smi.bin with "The Unarchiver.app" (free on the App Store here)
3. Convert System 7.0.1.smi to a dmg image using Disk Utility using the menu item 'Images > Convert'
4. Open the resulting System 7.0.1.smi.dmg and get the Fonts.image inside
5. Convert Fonts.image to a dmg using Disk Utility
6. Open the resulting Fonts.image.dmg
7. Enjoy your retro goodness.

Oddly, the Krungthep font currently supplied with OS X, while a Thai language font, has the latin characters drawn in Chicago.

I found this out here while trying to figure out why the Krungthep chosen by a non-technical friend for the headings of her website design looked so familiar...

An update for El Capitan:

OS X 10.11 has a new Disk Utility that can't do what the current best answer suggests. We need to adjust what we do on Steps 3 and 5.

Once you've used Unarchiver to unpack the .bin file from Step 2, jump into Terminal (I'm going to assume basic familiarity with how to use the terminal) and issue the following the command:

hdiutil convert System\ 7.0.1.smi -format UDRO -o sys7.dmg

This will give you a mountable image for System 7 named sys7.dmg. Mount it and copy the Fonts.image out to, say, your desktop. We need to do the same thing again on this fonts file.

hdiutil convert Fonts.image -format UDRO -o fonts.dmg

Voilà! We now have a modern, mountable disk image called fonts.dmg. All System 7 fonts will be inside, including Chicago. Double click a font to install it on your computer.