Most have not heard of Stanislaw Ulam (1909-1984), or if they knew them then it was as the
of John von Neumann or as the "co-inventor" (in fact he was just the inventor) of the hydrogen bomb. This is their loss. As his book
Problems in Modern Mathematics
Analogies Between Analogies
(among others) show, Ulam was one of the most original minds of the ages, and one who "threw out" ideas.
Los Alamos Science (1987) has published the conversations recorded between Ulam and Gian-Carlo Rota here . Some gems: