I decided to try Arch Linux on my notebook. The reasons don't matter.
However, there was this problem about the CD drive being broken, and the lack of a floppy drive.
So, how did I do it?
I had a partition I could destroy (/dev/hda3)
I installed qemu.
Then, I started qemu using the whole HD and a CD ISO image (booting from the CD!):
qemu -hda /dev/hda -cdrom arch-0.7.1.iso -boot d
Then, very carefully I installed it on hda3 and did not install GRUB.
Copied the kernel and initrd images to /boot on the other linux installation.
Edited grub.conf, adding the Arch entry...
And it worked.
Keep in mind that if you make a mistake, this will completely destroy all your data. But if you are careful, and have enough space, you can install your next Linux while you use your current one.
Now, is that cool or what? :-)