Microsoft co-founder Paul Allen has put his personal collection of Digital Equipment Corporation (DEC) minicomputers and mainframes online at PDPPlanet. Nostalgic programmers (and modern-day code jockeys who want to see what life was like in the olden days) can apply for an account and (re)discover the joys of developing on a PDP-10 running the TOPS-10 operating system or even a "PDP-10 clone, the XKL Toad-1 System, running the TOPS-20 operating system."
Paul writes in an introduction to the site:
"I hope you enjoy learning more about these remarkable machines. I certainly had a ball using them in their heyday—from the late 1960s to the early 1980s! During that period almost all Microsoft development was done on these platforms."
He doesn't discuss the delicious irony of making these machines available to present-day users as an on-demand service, via the Web. But then that's probably because in those days, everyone accessed this kind of computing power from a thin client, so the concept is hardly new. Only then it was called 'timesharing'.