How VisiCalc’s spreadsheets changed the world

It's the 40th anniversary of VisiCalc, the first popular spreadsheet program, and the anniversary has prompted some new remembrances of the killer app that, true to its "power to the people" origins, got people playing with data - and, by popularizing personal computers, helped to change the world. Something about spreadsheets popularising the PC always fascinated me. Out of all the things computers can do - it's tabulating numbers that played an important role in their spread.