I'm a big fan of the Trademark Move perk in GURPS, as described on DF2 p. 27. So I mention them a lot in my summaries, because they come up so often.
Here are three Trademark Moves form my current game.
"Borriz's Tricky Double-Tap" - Borriz Borrizman
Mace Swing/Skull (-3), Rapid Strike (-3/-3), Deceptive Attack -4 (-8), +1 for TM = net -13
Note that Borriz has Axe/Mace-28 and a Balanced weapon (+1 to hit). He also has Weapon Master, and Slayer Training (Slayer Swing at Skull), which accounts for the lowered penalties for some parts of his TM. Two skull shots on a 16 or less. Borriz started with this TM, and hasn't done much with it except expand the Deceptive Attack level as his skill has climbed from "high" to "highest."
I used this as the basis for Tarjan's Twofer, my morningstar-wielding knight's attack in the short-lived game I played in.
The upside of this one is clear - it's an efficient killer against things with the Skull hit location. Those without, it's useless, but it does mean for quick elimination of foes with natural limitations.
Raggi's unnamed Trademark Move - Raggi Ragnarsson
Greataxe Swing/Neck (-5), Deceptive Attack -1 (-2), +1 for TM = net -6.
Raggi has something like a 21 skill before this TM, usually giving him a 15 or less to pull it off. Raggi also has Cleaving Strike, and this makes a tremendously synergistic move with it. I suppose "leg" might be better, but Raggi has zero interest in "I leave a carpet of one-legged wounded in my wake" and total interest in "You'll know me by the trail of headless corpses." Besides, Slayer Training (Swing to Leg) isn't on offer in DF11.
Raggi added this somewhere along the line. Against foes with a the Neck hit location, it's been really effective, mostly because of the x2 injury multiplier.
Vryce's unnamed Trademark Move - Vryce
Greatsword Swing/Body (-0), Rapid Strike (-3/-3), Deceptive Attack -3 (-6), +1 for TM = net -8.
Vryce has Two-Handed Sword-26 right now and Weapon Master. Most of his other frills are defensive, not offensive. This is a very good TM to have, because it's almost universally useful. That also speeds up play immensely - it's rare that he needs to vary from this, so he can start rolling and I instantly know the margin of success needed to defend.
This one has changed during play, as Vryce's skill has gone up. At this point Vryce can pull this off on a 16 or less even on bad footing (-2). You might that was very risk-averse but it's not if play in my game."Bad footing" and its attendant -2 to hit / -1 to defend is a very common thing in my games. He may have changed this - I don't have his current sheet with me - but my notes still say "DA -3." That'll probably change as his skill creeps up further.
Like I said, this is almost universally useful, especially for someone who isn't looking for a quick incapacitation (Borriz) or knockdown (Raggi), but rather for the fastest route to -5xHP versus the most foes. Since nothing in TM says you can't split the strikes, Vryce uses this to quickly take out fodder in great numbers, too.
No one else has jumped onto TM, yet. I think this is because the other folks either have to vary their targets up too much (the Scout, for example) or just don't have the raw skill and power to benefit from locking themselves into a regularly valuable move.
As you can probably see, I don't strictly enforce the "entire turn's worth of actions" requirement - as long as it's a fully described and discrete action that has no moving parts on it. The three above are like that. All three speed up play a lot, and are will worth the tradeoff for the player and the GM. All three speed up play, because there isn't any fiddling around with modifiers, so flexibility on who gets hit or how the PC launches the strike is fine.
Trademark Move is one of those ideas that can easily port over to D&D games, too. Give each character (or, if you prefer, each fighter-type only) a "Trademark Move" slot. They put a turn's worth of actions, with all options that are relevant, into that slot. In return, they get a +1 to hit when sticking to that plan exactly. In games where the options are pretty much Attack and Do Something Else, this won't matter much or add much. But in any game where you can make per-turn decisions, offering to move those per-turn decisions to the pregame in return for a bonus for sticking to it has a place.