Okay, here's the list of avatars. I'll update this list as often as I can.
Last updated Feb 3 2008.
Already Done -
Gandalf
Constrictor
Green Goblin
Spider-Man
Doc Ock
Vulture
Spider-girl
Beast
Human Torch
Jack of Hearts
Wolverine (Blue & Yellow)
Venom
Terrax
Sasquatch
Batman
Silver Surfer
Bender
Punisher
Elektra
Hawkeye
Booster Gold
Ghost Rider
DragonMan
Annihilus
Wolverine (Yellow & Brown)
Thanos
Dr. Strange
Firelord
Deathlok
Tigra
Black Cat
Gladiator (Imperial Guard)
Cyclops
ROM
Joker
Saint of Killers
Gold Bucky
Wolverine (A.O.A)
Archangel
Nick Fury
Superman
Dr. Doom
Chewbacca (as Stormtrooper)
Rorschach
Hulk (Green)
Loki
Hal Jordan
Wolverine (Logan)
Havok
Kyle Rayner
Cyclops (Jim Lee)
Iron Fist
Plastic Man
Daredevil
Blue Beetle
Mr. Miracle
Superman (Kingdom Come)
Ironman (Stealth Armor)
Dr. Midnite
Black Vulcan
Luke Cage
Captain America (Black)
Union Jack
Ddura
Tony Coca
Captain Britain
Galactus
Gladiator (DD villain)
Valkyrie
Nightwing
Rocketeer
Baron Blood
Adam Warlock
Ash (Army of Darkness)
Sunspot
Rogue
Doc Savage
The General
Thor
Spawn
Smasher (Imperial Guard)
Solomon Grundy
Jackal
Colossus
Nova (Male)
Kang
Oracle (Imperial Guard)
Huntress
Eternity
Mystique
Sentinel
Nightcrawler
Guy Gardner
Sinestro
Black Bolt
Harley Quinn
Wonder Woman
Powergirl
Zatanna
Black Canary
Juggernaut
Magneto
Red Angel
Vapor Man
Gravity Girl
Meteor Man
Nighthawk
Beta Ray Bill (Thor)
Beta Ray Bill (Original Costume)
Nova (Frankie Raye)
Human Torch III (Frankie Raye)
Marvel Girl
Polaris
Space Ghost
Apocalypse
Vision
She-Hulk (ouch!)
Mysterio
Domino
Grand Moff Tarkin
Grendel (Hunter Rose)
Hellblazer
Princess Leia
Fin Fang Foom!
Xemnu
Googam
Alex (A Clockwork Orange)
Ironman (current armor)
Morbius
Dazzler (disco)
Medusa
Talisman
Snowbird
Stan Lee
Mercury
Rockslide
Surge
Wendigo
Judge Dredd
Cassidy
Jesse (eye patch/red eye)
Bi-Beast
PITT
Dust
Starbolt
Tempest
Titan
Electron
Hobgoblin
Neutron
Fang
Mentor
Impulse
Scintilla
Astra
Nightside
Hussar
Warstar
Magique
Manta
Quake
Works in Progress or Spoken For - In no particular order
Hobbit
Darth Vader
Deathbird
Ms. Marvel
X-23
Wildthing
Pluto
Yoda
Lockheed
Spider-Woman (Jessica Drew)
Banshee
Thing
Iron Man (80's version)
Iron Man (Original Gold Armor)
Maestro
Mr. Fixit
Hellboy
Marv (Sin City)
Snake Plisken
Two-Face
Goom
Rommbu
Red Ghost
Super Apes
Black Knight
Stingray
Jocosta
Mantis
Bette Midler
Fire
Ice
Red Tornado
Vindicator
Martian Manhunter
Robin (Tim Drake)
Hellcat
Son of Satan
Kyle Rayner (new costume)
Mimic
Ultron
Hawkgirl
Supergirl
Batgirl
Chaka Khan
Captain Marvel (Kree)
Captain America
Odin
Fiery Toe of Doom
Blink
Random
Marrow
Sunfire (AOA)
Darth Maul
Boba Fett
Saturn Girl
Phantom Girl
Storm (classic)
Marrina
Big Barda
Scarlet Witch
Ronan the Accuser
Dirty Socks
Underdog
Moonknight
Antman
Green Arrow
Edison, NJ
Hellion
South
Cloak & Dagger
Crystal
Aurora
Aurora (short hair)
Sven Goindenbloom
Darkseid
Death Dealer
Optimus Prime
Megatron
Soundwave
Archangel (Deathmask)
Goliath (Gargoyles)
Voltron
Green Lantern (Alan Scott)
V
Huntress (Earth 2)
Gambit
Hairy Toes
Swamp-Thing