People like Alfred Wegener, who came up with the idea of continental drift, for one; fossil collector Mary Anning, Cecilia Payne Gaposchkin, who first said stars were made up primarily of hydrogen and helium; chemist Douglas Prasher who was a car salesman when his colleagues won a Nobel (he's alive and back in reseearch, thanks to the publicity he got)..Arogyaswami Paulraj missed the bus because after a lifetime of unrecognized work he received the Marconi Prize for his work in developing LTE and WiMax.
Well, people like that who only those in the field will know as not being given sufficient recognition.
Hope that helps...