But somehow the back office software business manages to mint more than its share of the super-rich, it seems.

FORBES: See Who Got Rich This Week: New Groupon Billionaires, A Broadway Producer & More

QuickBooks has more than 90% retail market share for small business accounting software.

FORBES: Why Intuit Is More Innovative Than Your Company

That is why, as the stock market hemorrhaged when trading resumed after the tragedy, the share price of Viisage, a maker of facial-recognition software, more than doubled, the biggest gainer of any stock that grim day.

FORBES: Spotting Evil