Activating AA's is VERY useful, Clerics can use it to activate a mega heal button, a warrior for aggro, multiple DPS classes. Since we have so many slackers in DPS I am going to lay out each and every classes burn.

To activate a AA in a Macro first you need a AA list, like [url=http://forums.station.sony.com/eq/posts/list.m?topic_id=174445]This[url]. Some classes have their own list on their boards.

Once you have a list and know what you are gonna put in your AA, Open up the socials menu with Ctrl+O. Select a empty key and right click it, put in a name for the key and then,
1st line. /alt act ####, /pause 2
2nd line. /alt act ####, /pause 2

and so on, for disciplines its /disc (full and spell rank)
/disc Bullseye Discipline rk. III

Example:
/disc Bullseye discipline RK. III, /pause 5
/pause 2, /alt act 872
/pause 2, /alt act 184
/pause 2, /alt act 1460
/pause 2, /alt act 927