Hunter's Mark/Pet Attack:
/cast Hunter's Mark
Puts Hunter's Mark on something, and sends your pet in to attack. My pet and I are never attacking something without Hunter's Mark on it, unless I have a reason to be (trying to take on two things at once, etc.)
/cast [nomodifier] Arcane Shot(Rank 4); [modifier:ctrl] Distracting Shot
Hitting the button by itself fires off a mid-rank Arcane Shot; holding Control down fires off a max-rank Distracting Shot. After either one, you stop casting, so as to not break your own trap. The first one is useful for pulling things to where you want them to be while out solo'ing or questing; the second one I use in raids/instances, just to be sure.
/assist [tank's name here]
Useful in five-mans and some raids to figure out what the tank is targeting. Note that the tank won't always be targeting what you should be attacking, so use with caution!
"The" Infamous Macro:
/castsequence reset=3 Steady Shot, Auto Shot
/cast Kill Command
/script UIErrorsFrame:Clear(); UIErrorsFrame:Show()
Basic 1:1 Auto/Steady Macro. Not as DPS-heavy as a more flexible 3:2 macro, but also not a mana-eater like that one would be. I very rarely use this macro (we've had the talk about how I think it's boring, right?) and it's here mostly in case of emergency (for example: massive lag spikes during a boss fight which makes manual weaving impossible)
Not hunter related but...
Action Bar Lock/Unlock:
/run LOCK_ACTIONBAR = (LOCK_ACTIONBAR == "0") and "1" or "0"
Locks and unlocks the action bar with a button click. I keep the action bar locked 99% of the time (I haaaaaaaate randomly pulling something off of the bar in the middle of PvP/a boss fight), but sometimes you wanna move stuff around, so that's what this is for!
And, yep, that's it for my hunter-related macros. I also have several "fun" macros such as my Mount macro (uses Flying Mount in Outlands, and Normal Mount in Azeroth) and my random mini-pet macro (have I mentioned my bag space issues? Now you know why). But I figured I'd try to keep this post as hunter-related as I can.
What sorts of huntery (or even non-huntery) macros are your favorites?