The Top 10 List of Scientists should not be without the top 10 achievements, and so while lists differ with names for top 10 or top 100s (see http://www.adherents.com/people/100_scientists.html ), my choices contain both a) the software and b) the hardware and are given below in separate groups of health, tools, and knowledge.

Pasteur for discovery of germs
Salk for vaccination
Fleming for penicillin

Hubble for putting together the telescope
van Leeuwenhoek for producing the microscope
Bell for his work with the phone
von Neumann for computer

Bohr for the atom
Mendeleev for his achievement of the Periodic Table of Elements
Watson for tackling DNA

While the above achievements are certainly phenomenal and greatly appreciated, it seems that one or two names are sorely missing. Surely, Thomas Edison deserves mention for electricity (or at least the generating station), the Wright brothers for an airplane that could fly, and while no single person is credited with the invention of the auto, the United States was certainly advanced in manufacturing with the first company in 1893 for producing autos built by brothers as well, Charles and Frank Duryea. U.S. Patent for automobile date back to 1876-1895 and were owned by George Baldwin Selden, so let's include him as well.

Too good to do without for now we have usable power: Thomas Edison, Wright brothers, Duryea brothers and Selden