What if I told you that you could install some free software that would let you print to a PDF instead of to a hardcopy printer. You'd say – "so what?" I imagine. After all, OS X lets you natively print to PDF on every print menu. And there's nothing wrong with the PDFs it produces. So why on earth would you want to install extra software to do what the system does already?
Well, let's say you want to build an Automator action. Every time a file lands in a certain directory, you want to print it to PDF. You can't do that with the built-in PDF capabilities, because they require you to click on a drop-down and select ""Save as PDF." Or maybe you want to print from the command line – you have a whole directory you want to print. OS X supports printing from the command line ("lp -d "the printer name" file_name_to_print") and you can use wild card characters on the file name to print a whole directory. Again, without an actual printer installed, you can't do that.
Maybe you want to share out the printer – say to your non-OS X co-workers who don't have a way to create PDFs on their Windows machines. Yes, there are plenty of ways to get free PDF printers on Windows, that's not the point. The point is to do anything like this you need an installed "printer" of some type.
Adobe Acrobat used to install a PDF printer for you, but Adobe took that out in version 8 or 9 because of some compatibility problems they were having with the OS. And, of course, you had to buy a copy of Acrobat (not cheap!).
So how can you install such a printer? Well, if you're running Snow Leopard (10.6), you can install CUPS-PDF. This installer adds the drivers and a generic Postscript color printer to your system. After running the installer, open System Preferences and click on "Print & Fax." Then click on the + button to add a printer. You should see a printer called "CUPS-PDF" show up in the Default list of printers. Select it, then change the "Print Using" drop-down to "Select Printer Software…" and select the "Postscript Generic postscript color printer" (mine also says "rev3a" but depending on when you read this, it may change). Name the printer whatever you want, and share it out if you want.
If you decide you don't want it anymore, remove the printer from "Print & Fax" with the – button, then run the installer package again, only uncheck the two default selections and check the "uninstall" selection instead. The uninstaller won't remove the printer; that's why you have to do it yourself.
This package doesn't seem to work on 10.5 (at least it didn't for me). The installer runs fine, but when you go to add the printer it never appears in the list, so this appears to be limited to Snow Leopard users only. Of course, any other Mac can print to a shared version, so you can get around it that way. I know there are other version of the CUPS-PDF software around, but this one with the package is the first one I have ever got working right. So you might be able to find one for earlier versions of OS X and get one going.
Printouts go to /Users/Shared/CUPS-PDF/<your user name> as PDFs with names like "job_217-testmag_indd.pdf" (the internal print job number added to the name of the file or, in the case of Safari, part of the name of the web page.
CUPS-PDF will also come in handy if/when shared printers on a Mac ever work for AirPrint (printing from iOS devices).