The list of actions that provoke Attacks of Opportunity (page 141) list a lot of Do Not Dos in combat. Even in 1E and 2E, the DMs I played under sometimes allowed free attacks against foes that pulled some of these stunts.
Attack (melee) : A good idea, when someone's trying to kill you, to try to kill them.
Attack (ranged) : I fire my bow at the guy 5 feet away. Uh huh. Right ... and you're Legolas, aren't you?

Attack (unarmed) : If you have Improved Unarmed Strike, great. You know how to actually brawl. If you don't have that Feat, what are you doing? You're going to kick at that guy with the big sword ready? Good luck.
Activate a magic item, other than potion or oil: They strengthened this action in 3rd Edition.
Aid another: If you insist on kneeling down to save a comrade, that ogre standing over you is going to whap you. But that's better than your comrade dying, if you aren't killed ...
Bull rush: Still puzzling over this one.
Cast a spell (1 standard action casting time) : This is why spellcasters must be protected by the fighters! Sometimes the fighters forget to do this, and ...
Concentrate to maintain an active spell: This action has been strengthened in 3rd Edition. QUESTION: What, if anything, else can the mage do while concentrating?
Dismiss a spell: Obvious, this one.
Draw a hidden weapon: Still puzzling over this one.
Drink a potion or apply oil: Yeah, right. I drink my potion while ogre there is hewing at me. LOL.
Escape a grapple: Still puzzling that out. I intend an entire post on Grapple.
Feint: Still puzzling that out. A new action, it seems. Never heard of feinting in 2E or 1E.
Light torch: Common thing people do. Best to do it behind the protection of fighters ...
Lower spell resistance: Hmmm ... that's something you do to yourself. Similar to dismissing a spell ...
Make a dying friend stable: Obvious. Of course, if you're killed helping your friend, you don't help your friend. Decisions, decisions.
Overrun: Still puzzling this one out.
Read a scroll: For some reason, some mages think they can do this in combat without being attacked. I never understand that thinking.
Ready: In 2E, we had a version of this action. But they've formalized it here.
Sunder a weapon (attack) : Yes, he gets an AOO. But if you sunder his weapon, he's in real trouble.
Sunder an object worn/carried: Yes, he gets an AOO. But you can mess him up really bad, if you sunder something like a Girdle of Strength (yeah, I know, only + 5 in 3rd Edition, but still ...)
Sunder an object lying on the ground: No AOO? I'd think they'd get one. Hmmm ...
Total defense: Obvious.
Turn or Rebuke Undead: They've strengthened this in 3rd Edition, since it was a question mark in 2E whether the foe got a free attack.
Use extraordinary ability: Extraordinary ability is a new classification in 3rd Edition. Hmmm ...
Use skill that takes 1 action: (I'm assuming standard or full round action?) Hmmm ... it seems to me circumstances would vary with this one, but ok, they always get AOOs ...
Use Spell-like ability: Ok, they get AOOs here. So why not with supernatural and extraordinary abilities? Spell-like abilities must take more time and concentration, while supernatural and extraordinary abilities come without thinking about it, instantaneously. My guess.
Use supernatural ability: As above. New classification in 3rd Edition.
Move: Turning your back on a foe was always a bad idea, and in 1E and 2E they got free attacks on you too. Now it's worse, since every threatened square you move through provokes an AOO from a new opponent (fortunate, that each opponent only gets 1 AOO against you for movement. Otherwise, as you passed through the 3 hexes threatened by an orc, he's WHACK, WHACK, WHACK, on you.)
Control a frightened mount: Obvious.
Direct or redirect an active spell: Strengthening of this action from 2E.
Draw a weapon:
Did you know that, back in 1E, some of my DMs got so confused they ruled it took an entire round to draw a weapon?
A round was one minute. Picture that. (Fighter: UH ... I'm PULLING on it! ... I'll get it out one day ... it'll come out of the sheath any second now ... NUTS, it seems to be stuck ... UMMM I think it's out 5 inches now ... any day now I'll have that long sword out, yes sir ...)
Load a hand crossbow or light crossbow: Crossbows are a pain in the butt to use!
Open or close a door: Ok, they don't get AOO. But they might get Surprise. (Where's Lidda when you need her?)
Mount a horse or dismount: This one surprises me, that no AOO results. The cavalier will love this rule.
Pick up an item: I bend down and pick up my torch. Uh huh. All while the ogre is raising it's club to smash your head in ...
Sheath a weapon: This one surprises me, that they are allowed an AOO.
Stand up from prone: Obvious. (Which makes Trip really nice, eh?)
Ready or loose a shield: Hmmm ... ok.
Retrieve a stored item: I get out my flask of greek fire, rummaging through my backpack behind it. I pay no further attention to that ogre with the spiked club about to brain me!