Using the following two macros I boosted my threat-per-second from ~600 to ~900. No lie.
Heroic Slamming
A hard and fast rule of tanking is to queue up Heroic Strike every few seconds, provided you have rage to spare. This macro will queue it every time you use Shield Slam, which will be on a six second cooldown. This provides a HUGE boost in TPS and won't burn out all your rage on Heroic Strikes.
Code:
/cast Shield Slam
/cast Heroic Strike
Instant Revenge
Blocking and Revenge go hand-in-hand, why not make a macro that chains them together?
Code:
/cast Shield Block
/cast Revenge