A&E TV gives this list (pdf) for the top inventors of the 20th century.

15 Tim Berners-Lee World Wide Web
14 Stan Cohen and Herb Boyer Genetic engineering
13 Guglielmo Marconi Radio
12 Henry Ford Model T and assembly line
11 Gordon Gould Laser
10 Leo Szilard Nuclear chain reaction
9 Gregory Pincus Birth control pill
8 Alan Turing Computer
7 Nikola Tesla Alternating current
6 Jonas Salk Polio vaccine
5 William Shockley Transistor
4 Philo T. Farnsworth Television
3 Leo Baekeland Plastic
2 Wilbur and Orville Wright Airplane
1 Thomas A. Edison Light bulb, phonograph, alkaline battery

Of these, Ford and Edison got rich, but most of them never made any money off of their inventions.