First two posts, I talked about My own junk... my toon setup and my computer/software setup. Oh, those were fun times.. real romps through the backroads of my ego.

Ok, well, I DID slip in some educational stuff there.. along the lines of 'here's what I do'. Anyway, I thought I'd be a bit more helpful this time... giving some actual examples about one of my favorite subjects: Macros.

(Effectively) multiboxing would not be possible without the built-in Warcraft "follow" command and the ability to make macros.

Inviter

I've got a macro I call "inviter" that I keep in my general macros area on all my toons. Here's a pseudocode example (A1 stands for account 1, A2 for account  2 and so-on)... this assumes I'm running from account 1:

/invite A2_TOON1
/invite A2_TOON2
/invite A3_TOON1
/invite A#_TOON2
/ffa

When I hit this button, it tries to invite everyone at once and set loot to Free for all. In effect, whichever toons I have logged on on accounts 2 and 3 will get the invite, and the /ffa will fail because I have no group. I accept on account 2 and 3, then hit the inviter again. It will fail because the toons are either in my group already or not online, and the free for all will catch.
 
So, hit button, accept on 2 and 3 and hit it again for a ready to go party in FFA loot regardless of which combination of toons I have on.
 
 
Assistor (I bind to action key 2)

Assistor needs to be customized for the speicific toon you're on. I'm going to psudeocode here... fill in your own spell names for the capitalized names here

/assist MAIN_TOON_1_NAME
/assist MAIN_TOON_2_NAME
/castsequence reset=CD_VALUE_OF_OPENER_SPELL INSTANT_OPENER_SPELL, SOME_AUTOATTACK_SPELL
/startattack

Note that I have two chained assist calls. This is fine as an assist to a not-logged-in toon will just fail with no consequences. Basically, I always use one of my mele-capable toons on the main account as the "master", so the assists are hardcoded.

The castsequence has a reset=CD_VALUE_OF_OPENER_SPELL, so for instance on my mage, it's Arcane Blast, and the autoattack spell is "shoot":

/castsequence reset=8 Arcane Blast, shoot

NOTE: the /startattack line is to make sure that if something on the cast fails, they're at least in attack mode.

MainAttack (I bind to action key 1)

This one can vary depending on the toon in question... sometimes a single spell is fine, sometimes I want a castsequence, and sometimes a castrandom is in order.

I have a confession, I'm a button masher. I guess I got in the habit in the original Diablo where 1 click == 1 swing or 1 cast, so I tend to favor /castrandom macros with a list of various spells. It's never going to be as efficient as a spell rotation manually tweaked for each encounter, but welcome to the world of multiboxing where less is often more. Keep the activities you need to have simple and you'll be a lot more effective, and get it out of your head that you ever be able to play more than one toon at one time as well as a given number of single boxing players (unless they're all Mr. Bean or something).

Before I specced my mage hardcore into arcane, I had the main set up

/castrandom [channeling]; Frostbolt, Fire ball, Arcane Missiles
/startattack

The [channeling]; before the spell list makes it fall through and do NOTHING if I'm channeling (as in Arcane Missiles). Without this, you can end up stomping on your spell channel or keep restarting it thus wasting mana.
 
Nowadays, I specced my mage entirely Arcane, so it really makes no sense to cast non-arcane spells (unless I'm up against arcane-immune Mobs) so I've got it set up as:

#showtooltip Arcane Missiles
/cast [channeling]; Arcane missiles
/startattack

This lets me spam button 1 and it will cast arcane missiles every time that I'm NOT already casting it

Follower (I bind to the . key due to the way my fang is set up)

We are once again making good use of silent fallthrough. I start with my least favorite option (blithely following the party leader), then my (oh dear, the main's not on for some reason) third account (this assumes it's on my secondary account, adjust as needed), and finally the option thats most likely going to hit (the main account folks). THEN I hit /follow.

/terget party1
/target A3_MAIN TOON
/target A3_ALT  
/target A1_MAIN_TOON
/target A1_ALT
/follow

Now in theory, I could just do a bunch of /follow TOON_NAME, but Follower is dual-use for me. It guarantees that their target is back to my main. This allows me to always retarget a healer to my main toon without looking.. just hit follower (and quickly take 1 step back to keep them from moving if I want to keep them where they are) followed by a healing spell... so really quickly, (with my setup), if I wanted my priest to stop what she was doing and cast Prayer of mending on my main, I would hit  . (follower) s (step back) 8 (PoM)

Then go back to attacking by hitting 2 (assistor) and then spamming 1 (on my priest, that one is /castrandom Mind Blast, Holy Fire, Smite )
 
PRIEST SPECIFIC
Here I have two priest-specific macros that I use to keep my toons up when the excrement collides with the air circulation device. Nice thing is that binding heal gets both my toons.. yeah, if my priest isnt getting hit, it is wasted mana, but when things are going all pear shaped, it's about survival, NOT mana conservation. Spamming binding heals guarantees that both of my toons stay up until the priest dies or is CCd while I keep looking at what my main needs to do.
 
PoM is absolutely brilliant because it continues to bounce around while I go back to whatever it was I was doing (probably smiting) on my priest. The audible "bing" of the PoM bouncing from one to the other is helpful too - I know without looking if someone besides the mele takes damage... and if I count the "bings", I can tell when I need a new one. Since patch 3.0.2, it crits for about 3K healing - it's one of my most useful heals while dual boxing.
 
MainBind

/target A1_ALT_TOON
/target A1_MAIN_TOON
/cast Binding Heal

MainPoM

/target A1_ALT_TOON
/target A1_MAIN_TOON
/cast Prayer of Mending

Again, this is how I set stuff up and your milage may vary.

Next time: I dunno yet...