I'm surprised this wasn't submitted sooner. With today's 40+ GB hard drives, this doesn't matter to everyone, but this hint is useful if you like a clean system, with as few unnecessary files as possible, and want to conserve space on smaller hard drives.
Upon installation, the installer declares you need 3 GB to install when you click on a hard drive. 3 GB is what will be needed for a new clean install. However, if you click on the "Customize" button, you'll find options for the applications, language support, print drivers, etc. By de-selecting foreign language support files, and all the printer drivers, I was able to nearly cut the install size nearly in half, to 1.6 GB, also making it install faster!
This is true of every installer, but I was surprised at how much space was saved, and its a good reminder at every new major upgrade.
Mac OS X Hints