Well nuts--the Edmund filters appear brown over a mag-lite and shine a beam that is a deep red--but I have since been informed that you can actually see up to 1000+ nm, if it's bright and it's the only light there is.
So my dream of a flashlight invisible to the naked eye but visible to gen-1 NV is dashed.
(sob)
However, regarding the lighting gels that
webley445 mentioned--I looked for these and did find a source for the Lee filter gels near me. These are thin plastic colored sheets used for stage lighting, they cost about $6 for a 20 x 24-inch sheet, and you can cut them into any size or shape you want with regular scissors. The fellow on this page:
http://www.amasci.com/amateur/irgoggl.html mentions using Primary Red and Congo Blue--but there are better ones for longer IR filtering. The colors that you really want for IR-pass are #027 Medium Red and either #713 J. Winter Blue or #735 Velvet Green. One layer each of the red and either of the others looks BLACK in daylight on a sunny day--you can only really see the sun's disc through them, they are too dark to use for that guy's "$10 infared goggles", but a gen-1 NV scope can see right through them easily.
---The guy I got them from handed me a little designer swatch book as I was leaving, almost as an afterthought--and it has a little transmission chart for most of the colored filters that goes all the way up to 800 nm, so you can pick combinations with the transmissions you want. The reds have a transmission "hump" only on the long end of course, and the green/blues have a hump near 400-550 nm, and all also have an IR hump. The two combinations above are about the only two where the red transmission doesn't reach all the way down into the blue-green transmission--however, the light from both of these combinations *does* look blue-green, so there is some bleeding going on, but it was the best I could find going through all the colors. The website has the transmission charts as well, but online they end at 700 nm.
~