If you are looking for an autocast addon the best there can be found on curse.com, Quartz 3.
Besides autocast this addon will auto replace the default autocast bar from wow with something more shiny and eyecandy, it also has other use. At least for hunters and their blamed autoshot while moving that is coming with the next patch.
Every 3 second the hunter will autoshot with the ranged weapon, if he only stops for a second he will be able to autoshot again. You need to stop moving in order to start the cast timer for autoshot and to shot it, that will trigger again the start casting..
This is planned to get removed in the next patch, and hunters will be able to autoshot even if they will keep moving, no need to stutter step anymore. This if Blizzard won’t remove it.
Quartz can show you for now the autocast (autoshot)bar, if you want to disable everything and let quartz only just to show you the autoshot bar go into options and disable everything except “swing”.
You have plenty of options to tweak quartz, move the bar, use a specific color, etc.
This autocast addon can be used by any class, mostly it will redesign the casting bars and add timer bars.