Limited Editions
Limited Edition figures are Prizes at tournements, Mail-away figures or Promotional items.  They are usually exactly the same figure as the standard version, however instead of their code-name, their real-name is written on the base.  For example the Limited Edition Hulk is Bruce Banner.  The coloured ring on the base is gold/bronze on a LE figure  I believe that LE figures are not allowed to be used in official tournements.  Anyway... Here's a list (in no particular order) of the Limited editions so far, and what they do.  Enormous thanks to Warlock420 for his Dial genarator and list of figures and powers.
KNUCKLES - Limited edition Thug
This guy's essentially a veteran Thug with 2 extra clicks of 2 damage.  I'd assume this is because he's wearing brass knuckles.

JOEY THE SNAKE - Limited edition Henchman
Alledgedly appearing in an issue of Spider-man Joey is 1 point more expensive than a Veteran Henchman, and all round is generally a bit better.

OPERATIVE - Limited edition Hydra Operative
An operative with a higher attack value and a single click of Leadership.

MEDIC - Limited edition Hydra Medic
A medic with the ability to do 2 damage for her first click.

GABRIEL JONES - Limited edition Shield Agent
An agent with an extra click of 2 damage and a click of Leadership to represent this characters tenure with SHIELD.

TIA SENYAKA - Limited edition Shield Medic
A medic with a slightly better attack value and four full clicks of Support.

NENORA - Limited edition Skrull Agent
An agent with better attack value and a click of Energy Explosion.

RAKNOR - Limited edition Skrull Warrior
A warrior with better attack value and a click of Energy Explosion.

WILSON FISK - Limited edition Kingpin
Extra clicks of Leadership and Toughness.

MICHAEL JON CARTER - Limited edition Booster Gold
4 extra clicks with Energy shield after he loses Toughness will help this guy stay alive.

BRUCE BANNER - Limited edition Hulk
Gets Leap/Climb and Superstrength 1 click earlier than the Veteran.

BENJAMIN J. GRIMM - Limited edition Thing
Starts out with no powers and low scores to represent him before he became Thing, then he gains his abilities as normal, but only keeps Charge for 2 clicks.

ADRIAN TOOMES - Limited edition Vulture
Higher damage and defense as well as an extra 2 clicks of Charge compared to the Veteran.

KIRK LANGSTROM - Limited edition Man-Bat
An extra click of Charge and a click of Poison.

RAHNE SINCLAIR - Limited edition Wolfsbane
An extra click of BCF with a slightly higher attack value.

BLADE - Limited edition Blade
Keeps Stealth, BCF and Toughness for an extra click each.

VICTOR CREED - Limited edition Sabretooth
Kind of a combination of Experienced and Veteran versions, Creed gets Charge AND stealth at different points and extra clicks of Battle Fury.

WOLVERINE - Limited edition Wolverine
Charge, then Stealth and More Battle Fury.  This version of Wolverine is a little more of a berzerker.

CARTER HALL - Limited edition Hawkman
Charge and CCE as usual, but an extra 2 clicks worth of Leadership to lead the JSA.

ARTHUR CURRY - Limited edition Aquaman
Take a Veteran Aquaman, remove his leadership.  Add an extra click of health, CCE, Willpower and Toughness.

FRANK SCHLICHTING - Limited edition Constrictor
Just like the Veteran version but with a click of Defend so he can help protect others.

YELLOWJACKET - Limited edition Yellowjacket
Insane defense of 20, Leap/Climb and incapacitate.

NED LEEDS - Limited edition Hobgoblin
A click of Running Shot and increased attack value for his final RCE click.

SUPREME SCIENTIST - Limited edition Hydra Medic-thing
Some Support, some Incapacitate, some Energy Shield.  Bit of a mixed bag really.

FRED J. DUKES - Limited edition Blob
Somewhere in between Experienced and Veteran Blob with 4 clicks of both Toughness and Charge.

ANTMAN -  Limited edition Antman
Incapacitate and Stealth for the whole dial, 20 defense too, but still, 45 points for a character who does no damage?

DOMINIC PETROS - Limited edition Avalanche
Like the rookie version, but better.

PHILLIP MASTERS - Limited edition Puppet Master
OK?  EXTRA click of health, 3 EXTRA clicks with 1 damage instead of 0, ALL clicks with Mind Control and his Attack score has increased from 7 to 9.  Fairly good.

JARVIS TETCH - Limited edition Mad Hatter
If you want, for an extra 12 points you can use a Mad Hatter EXACTLY the same as the Veteran but with 2 clicks of Incapacitate.  No?  I didn't think so.

FRED MYERS - Limited edition Boomerang
Extra RCE, extra Incapacitate, and an Extra 2 range for 4 points extra compared to the Veteran.  Compare this to the increase in Jarvis Tetch's cost above.  They really must just make these numbers up.

ANNIHILUS - Limited edition Annihilus
Extra Invulnerable, extra Toughness and Pulse wave, at the expense of only having one attack.

SUPERMAN - Limited edition Superman
Much like the Veteran Superman however, He sacrifices one point of movement, and gets Hypersonic Speed for 3 clicks. And Instead of being an esteemed Justice Leaguer he's a Superman Ally.

THOMAS OSCAR MORROW - Limited edition T.O. Morrow
More Super-Senses, Energy Explosion, Force Blast and 2 clicks of support.

SELINA KYLE - Limited edition Catwoman
Fewer Super-Senses, a click of last minute Outwit, and re-arranged Incapacitate and Smoke Cloud.  Faster than the Veteran too.

TED KORD - Limited Edition Blue Beetle
More Leap/Climb less Force Blast, Incapacitate instead of Smoke Cloud, and some bonus Energy Explosions.  Faster than the Veteran and does more damage.

JEAN GREY - Limited edition Jean Grey
D'you know how they could REALLY improve Jean Grey?  Give her an extra click of Support and make her cost 9 points more.  What do you mean it would be better to just get an extra medic???

DR. HARLEEN QUINZEL - Limited edition Harley Quinn
One click she has Incapacitate instead of Smoke Cloud, and 2 extra range.

EDDIE NASHTON - Limited edition Riddler
Outwit and Mastermind.  Perfect.

SPIDER-MAN PROMO - Limited edition Spider-Man
Very like the Veteran Spider-Man although instead of Flurry he gats BCF.

CLAY QUARTERMAIN - Limited edition Shield Agent
Energy Explosion and Willpower, tough little guy.

AGENT BEAULIEU - Limited edition Shield Agent/Mandroid
TK, Incapacitate and Toughness, regulation Mandroid stuff.

PAIBOK - Limited edition Skrull
28 point Skrull with 6 clicks o' health and 2 of Toughness.

RACHEL VAN HELSING - Limited edition Vampire Lackey
Stealth, BCF and Steal Energy.  3 clicks of health.

FELICIA HARDY - Limited edition Black Cat
Leap Climb, Stealth and Probability Control, somewhere in between Experienced and Veteran Versions.

RITA DEMARA - Limited edition Yellowjacket
Not enourmously different from the standard version really.

DOCTOR DOOM - Limited edition Doctor Doom
Kind of a sub-Rookie.  Fewer clicks of health and all the same powers as Doom, but less of them.  And for only half the cost.

MORTIMER TOYNBEE - Limited edition Toad
Better than the Veteran.  not by much but he'll stay alive longer.

ELEKTRA NATCHIOS  - Limited edition Elektra (2nd spear-wielding version)
3 clicks of Flurry after stealth.  Not bad at all.

CLINT BARTON - Limited edition Hawkeye
Like the experienced, but with increased range, more shots and the Spider-man team ability.

BATMAN PROMO - Limited edition Batman
Weird little figure.  Most similar to the Experienced version but Less powers overall, Leadership instead of CCE.  An attack of 13 rather than 9.

JOKER - Limited edition Joker
Similar to the unique.  Lots and lots of energy explosion.

SUE STORM - Limited edition Invisible Girl
Experienced version, powers swapped around a little, and an extra click of her when she was 'normal' at the start.

JOHNNY STORM - Limited edition Human Torch
The rookie with a 'normal' click bunged on at the start.