Sandbot is a multiplayer bot for Half-Life, Half-Life Opposing Force (Deathmatch and Capture The Flag), Day of Defeat (Territorial Control), Gunman Chronicles, Natural Selection (Combat) and They Hunger.
Beta release of Sandbot - a bot for Gunman Chronicles and They Hunger. Extract to your Steam/steamapps/common/Half-Life directory.
Could be good.
If you try it let me know how it is. There's still room for improvement (especially the Gunman Chronicles part of it - the bots don't use any of the extra features of the weapons yet) but it's usable.