Chat heads is a great feature, Paranoid Android team took inspiration from it to make their own chat heads for all apps, with a nice pop-up window showing the complete app. In one word, "Halo".
Quite in the same time, Floating Notification project started: the goal is to have something similar to Halo and chat heads, but for every ROM, without needing root permissions.
This app is really nice and promising, congrats to the developers, they have a bright future in front of them.
[XDA] Floating Notifications
[XDA] Floating Notifications themes
Paranoid Android website
Many thanks to BBQScreen developer xplodwild ( xplod.fr ) to have made such a great application!