ChainMap is an experimental addon that I'm doing by myself and which use is to see raid members as they are around you, in a graphical interface; it will display in circles who needs some help and where your chainheal should be landing to achieve a better healing performance.
This addon acts like the spark component of the PitBull Unitframe addon which shows you when you get out of combat. This is especially useful in arenas where you have to drink. Note that drinking while in combat probably isn't intended to be possible, but due to a delay between your client and Blizzard's servers, it is. This addon was designed to make this process more efficient.