It is now possible to program your own scripts for combat, crafting, gathering, and more. The scripting language is in a very early stage, and many, many more commands will be added. That said, you should be able to create relatively powerful combat rotations simply by checking OGCD and GCD timers. Proc-based jobs will want to make use of the hotbar commands, and if you need to check for buffs/debuffs, you can do that as well. It is even possible to create an elaborate AST bot to use cards on certain party members based on their job and whether or not they already have the card active.
Check out the script guide here: Final Fantasy XIV Scripts - Speeder Cheats
