Thanks to the wonderful Bicycle Museum of Bad Ideas for cataloging all the versions of non-straight cranks from at least 1931 through today. Notable entries include:

• Agache 1931
• Rosa 1938
• P.M.P. “L” or “bent” cranks of the early 1980’s
• Z-Torque” as of 2012
• dpardo Sickle crank available today

As MOBI correctly points out

A moment’s thought shows a straight crank and an L crank always have the same relation between pedals, chain, and bottom bracket. Thus, there is no advantage to L cranks. And an L crank always has more material than a straight crank, so is always at a disadvantage for weight, strength, stiffness, and/or cost.

This is pretty good confirmation of the line about the rate at which suckers are born, no matter who said it.