Aside from my very top suggestion (being to give me back the crowns that disappeared in the auction house), my most wanted addition to Spiral Knights is sweet and simple.

At the end of every Left 4 Dead game, it shows end level titles or achievements or whatever that word is. Think, apply that to Spiral Knights levels! For example in Left 4 Dead, it would showcase the players who did the most damage, killed the most zombies, fallen the most times, plus corny ones like killed the most Smokers.

I'm not quite knowledgeable of how programming works so I cannot assume if this is easy to implement. Well, statistics would have to be recorded every level and from my perspective it looks pretty straight forward. It's probably not, anyway.

I've come up with a few stuff, not too much because I like to avoid gimmicky ones like Most Bombs Detonated and more useless specializing.

Also, some titles should only be given should their deciding value (damage, amount of blocks) reach a certain threshold. For example, the Most Energy Used title should only be given should one of the players use more than 150 energy. Some thresholds should be adjusted according to the stratum or depth level.

Most or all of the names sound cooler with a "The" added before. Try it in your mind.

Possible Showcases/Superlatives (Possible Names)

Most Damage Dealt (MVP, Destroyer, Clockwork Slayer, etc.)
Least Damage Taken (Agile, Quick, Wolver, Dodger, Mist, etc.)
Most Damage Taken (Team Player, Lemon, Meat Shield, etc.)
Most Damage Parried or Most Attacks Parried (Shield, Shielder, Defender, Defensive Player, Invincible, Indestructible, etc.)
Best DamageDealt:DamageTaken Ratio (MVP, Elite, Elite Knight, Spiral Knight, Pro, etc.)
Most Energy Used (Three Rings Benefactor, Shopaholic, Loose Wallet, Rich Man, etc.)
Most Attacks Missed or Most Attacks That Did No Damage (Clumsy, Unlucky, Trigger Happy, etc.)
Least Attacks Missed or Least Attacks That Did No Damage (Accurate, Practical, Pragmatic, etc.)
Most Kills or Most Last Hits (Pro, Last Hitter, DOTA Player, Vulture, etc.)
Most Times Revived (Lemon, Weight, Victim, etc.)
Most Times Reviving (Savior, Heat Stealer, Heat Hoarder, Heat Thief, Doctor, Medic, etc.)
Most Damage Dealt to The Boss (Boss Slayer, MVP, Carry, etc.)
Boss Last Hit (Boss Slayer, etc.)
Most Monsters Hit In One Attack With Sword (Big Sword, etc.)
Most Status Effects Taken or Most Variety in Status Effects Taken (Sickly, Fragile, Victim, Cursed, STD, etc.)
Most Health Pots Used (Hoarder, Pot Thief, Selfish, Pot Dealer, etc.)
Shocked a Quicksilver (Idiot, etc.)
Burned an Oiler (Idiot, etc.)
Joined in the Middle of a Level (Bastard, Immigrant, etc.)
Most Times Spiked (Impaled, Cheese, Spongebob, Hotfoot, etc.)

I don't know, it all sounds kinda fun to me. My personal favorites are the Three Rings Benefactor and the Bastard titles, hehehe.

EDIT:
The Spiral Knights achievements are colorless, not unique and overall boring. If these titles were integrated into achievements, it would make for a much more enjoyable experience. You can already imagine the fun in a group!

Different titles for the same showcase or superlative could correspond to the value itself, for example one player could achieve Most Damage Dealt and was titled for that level, The Destroyer. The next level, his friend wins the superlative itself but is titled Clockwork Slayer because overall he did more damage.

That way, perhaps earned titles could be worn in public. Perhaps you could only wear titles if you would earn them a minimum of 5-10 times. Players would work pretty hard for that, don't you think?

More title ideas:

Most Health Pots Used (Addicted to Pot, High on Pot, Pot Addict, etc.)
Shock a Quicksilver with a Static Flash (Newbies FTW, Newbie King, Newb Lord, etc.)
Most Crowns Used On Recipes (Shopaholic, Loose Wallet, Basil's Favorite Customer, etc.)
Most Time Spent Dead or Spent 3+ Minutes Dead (Unwanted, Dead, etc.)
Least Damage Taken (Untouchable, etc.)
Spread a Status Effect (STD, etc.)
Gave Someone a Health Pot (Mother Theresa, etc.)
Accumulated 3 Mechaknights (How?, Mechanic, Wrench Master, etc.)
Killed by a Gremlin Healer's Emberbolt (That Was Embarassing, Pissed His Pants, Once in a Blue Moon, etc.)