I really like the interact lines in Pitbull but they don't show much information for healers. Because my raid is mostly using forecast I decided to modify the InteractLines module to show forecast data. When someone starts a heal it shows a yellow line from the player to his target whichs fades depending on casttime.
Before you look at the attachment you should know that it's only a quick write and I only did a short test. You also still need Forecast to send your casts to other player. It's meant to be an example and maybe someone will make a clean version of it or it will integrate it in the official Pitbull.