The small handheld strobe light with an IR cover was vital both mounted and dismounted in my Stryker company. There are also very small, 'firefly' or 'Phoenix' beacons that clip onto a 9v battery. They are programmable so you can make a distinctive long and short light pattern. (One long for 1st PL, one long one short for 1st pl 1st sqd etc)

I know here at NPS they are working on enhanced IFF patches to wear on the uniform. Instead of just being passive reflectors like is worn today they detect certain wavelengths of light (for example the wavelength of IR aiming lasers) then, when detected emit a pulsing IR response. That would be a nice addition to a kit bag when fielded.