Hi.

> Is it possible to boot to grub and in its menu choose between either doing
maintenance on the
> current hard disk or running the installer to install a basic debian
> system on a new hard disk?

Last xmas i do something similar for some customers.
My usb-key drive was so 'configured':
- a multimedia distro: geexbox
- a tiny debian distribution: DamnSmallLinux
- a tiny System Utility distribution (Gentoo based): SystemRescueCD
- a tiny Slack distro: Slack PopCorn Edition
...all bootable from Grub.

And there was also installed WinPenPack to allow to run some GPL
applications from Window$ without install anything.

I don't remember well the way i do that, but all i remember is:
1 - install geexbox on the usb-key (you can do that with 'hd-install' option
while booting geexbox);
2 - copy all the DamnSmallLinux, SystemRescueCD, Slack to the root
partition;
3 - edit the grub (installed by geexbox) with the new kernel and verify
device.map;
4 - personalize grub - background, timeout, default etc etc;

So, the way i do that is installing on yhe usb-key a distribution that allow
the boot via grub (not syslinux).
>From that there was not problem.

If you want i can share this usb-key image (only 512 MB!!), so you can look
at that.
Hope it s you!
Bye!