This isn't really a hint, but I was thrilled to see it when I did. I haven't seen anyone else mention it, so I will: When booting from the 10.4 DVD, one of the tools available (along with Disk Utility, etc) is the Terminal!
Since Apple's made things trickier for using single-user-mode for anything much more than cp or rm, it's nice to have a Terminal available, along with Disk Utility, while you're working on a sick machine.
[robg adds: I only happened to notice this because I needed to use Disk Utility while booted from the DVD, so I figure it's worth a mention...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050510151249986