Health and Medicine -- digital-imaging breast-biopsy systems, arteriosclerosis detectors, ultrasound scanners, MRI, portable x-ray device implantable heart aids, cataract surgery tools… and more.
Environmental and Resource Management -- solar energy devices, weather forecasting aids, sensors for forest management, environmental control and pollution measurement and control, radioactive leak detectors, earthquake prediction systems, sewage treatment devices, energy-saving air conditioning and air purifiers… and more.
Public Safety -- radiation hazard detectors, pen-sized personal alarm systems, lightweight cutters for freeing accident victims from wreckage, lighter-weight firefighter's air tanks, Doppler radar, fire detectors, corrosion protection coatings, protective clothing and robotic hands…
Consumer/Home/Recreation -- water purification systems, the Dustbuster, shock-absorbing helmets, flat-panel televisions, high-density batteries, trash compactors, freeze-dried food packaging, sports bras, hair styling appliances, composite golf clubs and hang gliders... and more.
If you want a comprehensive accounting of the spinoffs that you've paid for, check them out yourself.
There's another way to look at the return on investment from space exploration. Tony England, a University of Michigan engineering professor, looks at the ROI by posing the question: Are NASA's programs still relevant? His response: "On the 40th anniversary of the lunar landing, it’s appropriate to assert an emphatic 'yes.' Human spaceflight will eventually answer the question, 'Do humans have a viable future beyond the Earth?' A great society needs to invest, at some effective level, in pushing back its boundaries -- both its knowledge boundaries and its physical boundaries. NASA's programs are one of the ways we do this."
To be or not to be? To explore or to not explore? Those are the questions. I choose to be and to explore. My outlay for cable TV exceeds what I pay for U.S. space exploration. If I had to give up one to have the other, I'd pitch my cable box. Then I'd go out and look at the sky -- just as I did 40 years ago -- except this time I'll be wearing polarized sunglasses, my cool running shoes and a pretty-good smelling shirt (even if I'd had it on all day). Oh… and I'll probably grab a glass of Tang.