A little list for some cool looking Glows for NPCs. Hope you enjoy, you can add some in the Comments and I could add them here.

•Left 4 Dead Survivor Outline
player_halos_npcs 0.3 0.4 1.0

•Left 4 Dead Green Outline
player_halos_npcs 0.0 1.0 0.0

•Left 4 Dead Yellow Outline
player_halos_npcs 1.0 1.0 0.0

•Left 4 Dead Red Outline
player_halos_npcs 1.0 0.0 0.0

•Pink-ish Color Outline (Almost close to a Puked Survivor or Biled Infected)
player_halos_npcs 2.7 0.1 1.5

•Orange Color Outline (incapacitated)
player_halos_npcs 1.2 0.45 0.0

•Light Purple Color Outline
player_halos_npcs 0.75 0.35 0.85

•Cyan Like Color Outline
player_halos_npcs 0.20 0.84 1.0

•Lime Like Color Outline
player_halos_npcs 0.75 1.0 0.10