In recent news, a link to the following site was buried; I figured there might be others interested in giving this a go:
unix50.org is a service of the SDF Public Access UNIX System!
Find out more about the SDF at sdf.org
When you connect you'll be able to CREATE and DESTROY an entire UNIX system on a whim.
Use unix50.org to learn about old and significant versions of UNIX on emulated hardware.
UNIX Systems available
UNICS (Version Zero) PDP-7 Summer 1969
First Edition UNIX PDP-11/20 November 1971
Fifth Edition UNIX PDP-11/40 June 1974
Sixth Edition UNIX PDP-11/45 May 1975
Seventh Edition UNIX PDP-11/70 January 1979
Research UNIX 8 VAX-11/750 1981
AT&T UNIX System III PDP-11/70 Fall 1982
AT&T UNIX System V PDP-11/70 1983
AT&T UNIX System V 3b2/400 1984
4.3 BSD MicroVAX June 1986
2.11 BSD PDP-11/70 January 1992