Via PCLinuxOnline, MEIPS is a Debian-based distro that allows you to both boot from a LiveCD and install to your hard drive. Of course Knoppix is the king of LiveCDs, but the last time that I installed it to a local hard drive, it still behaved like it was running on a CD, just from my hard drive. Of course there are ways around it, but it’s a little awkward.
It looks like MEIPS does a good job of allowing you to play around with Linux, and then easily install it to your hard drive if you so choose. From what I’ve seen of the installer, it looks pretty intuitive and pretty straightforward. Because it runs from a full-on KDE session, you don’t have to deal with those useful but unsightly text menus.
I have not had a chance to give this a try, but it looks promising. It is based on Debian unstable and of course you can use all of the apt goodness once you have a working installation.