What's the longest wavelength of infrared that anyone has ever seen?
Everyone can easily see the light from an 808 nm laser pointer. ("Visible light," 400 - 700 nm, just means whatever wavelengths most people can easily see under ordinary circumstances, not counting lasers and such.)
940nm tactical flashlights look very dim, but you can still see the light. Some people at Laser Pointer Forums (dot com) have seen the light from their 980 nm laser pointers. In one vision experiment people saw 1064 nm (http://www.opticsinfobase.org/josa/abstract.cfm?uri=josa-66-4-339).
Researchers suspect that people can probably see 1100 nm, and that the upper limit may be 1150 - 1200 nm, but they're not sure. Most of my sources are decades old, so I was wondering if anyone ever got any higher than 1064nm.