Rolodex
A Rolodex is a rotating file device used to store business contact information (the name is a portmanteau word combining Rolling and Index) currently manufactured by Newell Rubbermaid. The Rolodex holds specially shaped index cards; the user writes the contact information for one person or company on each card. Many users avoid the effort of writing by taping the contact's business card directly to the Rolodex index card. Some companies have produced business cards in the shape of Rolodex cards, as a marketing gimmick.
The Rolodex was invented by Arnold Neustadter in 1958. Neustadter also invented Autodex, a phone directory book that automatically opened to the right letter, Swivodex, an inkwell that did not spill, Punchodex, a paper hole puncher, and Clipodex, a stenographer's aid that attached to the knee.
Rolodexes are still common, despite many computer applications that perform the same function.
The name rolodex has become somewhat genericized for any personal organizer performing this function. Of particular interest to students of business economics is the card-index system with which the famous American economist Irving Fisher is said to have made his fortune. Fisher's book on 'The Theory of Interest' (1930) revealed the organised mind of a well-organised teacher - who had earlier tried to illustrate his theories by constructing working engineering models. John Maynard Keynes used Fisher's text as a benchmark for his own 1936 critique of neo-classical economics "The General Theory of Employment, Interest and Money". Fisher also revived The Quantity Theory of Money - whose usefulness has aroused more controversy over the years amongst economists than the revolving card-index system he developed that conforms to the generic term 'rolodex'.