I swear the amount of times someone just drops it behind a random wall or a bush. Anyhow, im thinking about something abit like the corpse icon indication thingy that engies get, only with a sane range limit (50 meters?).
Seems like a nice idea, but there's already a lot of ideas for the L4D-styled glow. Man, people are going to have to take loads of glow colours into account :p