Debuffs are an essential part of any major combat scenario. Every so often I can hear from my vent a "damn, why does he keep hitting me with that?" or "Argh, not again!" Yet despite their annoyance they keep battles somewhat interesting. While FFXIV has a good deal of basic debuffs I'm sure there are plenty more that can be added.

What kind of devilishly devious debuffs would you or like to see added to the game?

Some off the top of my head:

Knockdown - A powerful strike has thrown you to the ground, prone.
Grappled - You're held by an enemy and can't escape!
Nailed - You've been nailed into the ground and can't escape without assistance!
Floating - You're floating above the ground. Movement becomes slippery(like sliding across ice)
Dazed - You've been put into a daze. Can't take actions, movement is staggered and random.
Confused - Hotbar changes to one button "???". Actions are random or occasionally fail.
Enraged - You attack without control! No effect on warriors.
Encumbered - You're holding something weighing you down. Drop or toss the item!
Chained - You're being chained down! Run away to break the chain or be wrapped!
Wrapped - You're wrapped in chains and can't act or move. Have someone free you!
Marked - You've been marked by an enemy for some devious plan. (Used occasionally already)
De-spirited - You need some cheering up. (;D) Damage lowered; TP/MP cost higher.
Frozen(blocked) - You've been frozen into a block of ice! You need heat to be thawed. Can be unfrozen through a blm fire spell or a ??? Mage casting Melt
Melt - You're armor has been soften! Damage taken increased.
Drenched - You've been drenched in water. Thunder abilities do more damage to you.
Nightmare - You're suffering from terrors in your sleep causing damage over time. Can only be applied while slept.