Science is riddled with great ideas be laughed at or ignored. Mostly ignored. A Short History of Nearly Everything covers so many of the large discoveries of the last few hundred years and so discoveries were largely unnoticed or unappreciated until well after the inventors death.
In Geology William Smith was the first person to draw a geologic map of anywhere. It was largely ignored and Smith ended up in financial ruin and debtors prison after spending a good portion of 20 years working on it. People thought the map was a neat summary of England but it was hardly profitable. He ended up being pretty lucky in that within his lifetime the brilliance that is a geologic map was recognized and began to be used more widely. The use of maps such as his made it possible to very accurately predict where coal seams would be, a lucrative business. The guy is essentially the father of geology but at the time was just some guy taking his investors money and not getting anywhere.
His Map - http://eoimages.gsfc.nasa.gov/images/imagerecords/8000/8733/strata_england_wales_1815.jpg
Another geology example and one that's from pretty recently is plate tectonics. Plate tectonics (subduction and all that) is seen as sort of the Grand Unifying Theory of geology in the way it ties together almost all aspects of geology. Unfortunately it was almost entirely ignored when Alfred Wegner proposed the idea in early 1900s and big players in the geology and geophysics field were pretty critical of the such a left field idea. They may have laughed but history didnt record it as its much easier to remember scathing reviews than laughter.
It was until the 60's (only 50 years ago) that we had strong enough evidence to satisfactorily support plate tectonics. Hell even some textbooks from the 70's didn't agree with plate tectonics but the theory holds together almost all ideas related to geology.
In the 1940's a geologist named Reg Sprigg was working for some mines in the Hills near Adelaide, Australia when he discovered what he believed to be multi cellular fossils from rocks older than any known multi cellular fossils. They are very weird looking so its not suprise no one really thought he had found fossils. His paper for the prestigious journal Nature was rejected and upon presenting to the International Geological society most people shrugged and patted him on the head. The fossils are entirely unique and wildly strange looking compared to life after it and the discovery pushed the date for the appearance of complex life back one to two hundred million years.
If you want stories like this I really recommend A Short History of Nearly Everything. It is basically a summary of all the discoveries in all the STEM sciences and how thoroughly each discovery was ignored or ridiculed.
