Current Entrants

Martijn Benschop
SPARTAAAAAA
The 51st shade of grey

Samuel Park
Bowser
Bouldergeist

Jack Tweedy
Master Chief

Ceri Jenkins
Captain Marvelous
The Eleventh Doctor
Judas Volturnus
The Meaning of Life

Max Medhurst
Neo
Sheldon cooper
Mrs Richards
A phone calling Orange's customer service

Alex Holt
Old-age Cosmic Temminck's Stint Knight
A lifesize origami recreation of Noah's Ark (containing all animals in paper)
A genetically engineered superbeing made from the DNA of all vapourboteers ever
A jar of pickled Oddish

Lian Walsh
Chuck Norris riding a motorbike made of human skulls
Howard Jones #1
Howard Jones #2 (formerly of Killswitch Engage)
AJ Styles

Archie
Yoda on a boat
Stormtrooper in a car park (ala )
Baby monkey on a pig (ala )
Inflatable novelty hammer

Jordan Brown
Batman 1000000 (ala this ) with prep, Adam West's utility belt and Grant Morrison writing

Tracy Farber
Lancer (Fate/Stay Night)
Shino bodyswapped mentally into the body of Kenshiro (.hack//GU/Fist of the North Star.)
Ovan on helium (.hack//GU)
Kyubey (Puella Magi Madoka Magica)

Joey McConnell
A large three metric tonne bag of Rockets (as in the candy)
Three Kerbal astronauts
Franco-era Spain
Father Jack Hackett

Nick Schuch
That feeling that you get when you step out of a hot jacuzzi and into a cold swimming pool

That's 35 entries so far. Martijn said there'd be more to come. Hopefully this is the case, and not just from him. Get more in, people!