ActionQueue is an AddOn that allows you to queue up actions that may be
executed when the user uses a binding that does not perform an action
itself. This allows for semi-automatic spellcasting et cetera.

ActionQueue hooks bindings that deal with player movement and camara
change (ActionQueue_Hook.lua has a list of the functions that the
bindings call). When these bindings are called, it first performs the
hooked action, and then examines its queue and executes any action that
is pending.

http://www.curse-gaming.com/mod.php?addid=2948