ibiblio has a number of old distributions, including MCC (the first distro), SLS (which was so bad it inspired both Slackware and Debian), and Yggdrasil (the first commercial distro):

http://www.ibiblio.org/pub/historic-linux/distributions/

Here's how to run them using qemu:

http://www.freesoftwaremagazine.com/node/2097

And some history:

http://lwn.net/Articles/91371/