TooCool - displays cooldown of abilities on your action bars. Currently only supports FlexBar and the default Blizzard action bars. However, adding other bar mods is easy; take a look at GenerateFlexBarButtonList() and GenerateBlizzardButtonList(), the calls are made in the OnEnable() function. Essentially, you make a function which returns a table of strings which contains the button frame names that you want to add cooldown count to.
It is set up by default to only support Flexbar, if you use the Blizzard bars, uncomment line 21. Additional configuration methods are forthcoming.