A CD-less OS Install. 
note: you need a mac with a minimum of OS X 10.3 installed on it already.*

Once upon a trackpad, my trusty PowerBook G4's SuperDrive had failed. Sadly, since it was still running Tiger, I really needed to upgrade to Leopard. After much searching, I never found anything of use, until it hit me. Why not partition the HD and put the OS installation on that! It will be much faster than doing it from a CD anyway. Now, at this time, I couldn't boot from a USB drive (for unknown reasons), so this is really if you can't or don't want to boot from a USB drive. 

1. Rip OS X to your machine.

For this guide, I am using Leopard.  You need to put your OS X install DVD into a Mac with a working DVD/CD drive, any will do, as long as it is running at least 10.3 (10.4+ recommended).  Open Disk Utility and select the OS X install DVD. Click on 'Make new Disk Image' in the tool bar. Save it to your desktop, the name doesn't matter. 

2. Partition and restore.

By some means, get your HDD out of the Mac with the broken CD drive and connect it to the Mac with the ripped copy of the OS X installation on its desktop. You can connect it by any means necessary. Next, if you aren't afraid of losing data (or this machine has Leopard on it) go ahead and erase and partition the HDD. One of the partition needs to be 6GB and the other can take up the rest of the HDD's space. Once it is partitioned, select the 6GB partition, click on the 'Restore' tab, and drag the OS X disk image from the desktop into the 'Source' field, and drag the partition into the 'Destination' field. Click restore and wait until completion. 

3. Replace and install.

Once your HDD has got the 6GB OS X install partition on it, go ahead and put that HDD back in the Mac in which you are to perform the upgrade on. Boot the machine and when you hear the chime, hold 'option' until the drive select menu appears. Boot into the OS X install partition and install, making sure you are installing into the bigger, OS X partition, not the OS X install partition. 

3. Removing the OS X install Partition. (Optional)

This only works on Leopard. Whenever you have finished installing Leopard, you can open Disk Utility and remove the OS X install partition, and make the OS X partition larger, using the space previously occupied by the Install partition.