The following are some example macros. Please feel free to add your own in the comments.
Use with a string variable to set things that need to be targeted at particular points in the fight. Originally created for the Head of the Headless Horseman - since has been used in for the chains in the Terestian Illhoof in Kara and Chaotic Rift's in Anomalus fight in Nexus.
/cast [target=$tank,help,nodead][target=mouseover,help,nodead][target=pet,help,nodead] Misdirection
Basic misdirection macro to always go to the tank when in a group. Assign the tank's name when joining and use without worry afterwards.
/cast [@$maintank,help,nodead][@$offtank,help,nodead][@mouseover,help,nodead] Beacon of Light
Basic Bacon macro to always go beacon the maintank when in a group or fall through to the offtank if the main tank dies. Assign the tanks' names when joining and use without worry afterwards.
/cast [target=$vig,help,nodead] Vigilance
Set my vigilance target (usually highest dps or another taunter) for easy refreshing when running as a group.