Um, kinda pathetic the first thing that came to mind was:
Kurosawa Kakeru or Kitahara Aya from "Onani Master Kurosawa"
.... but, anyways, off the top of my head.
Yako Katsuragi from "Majin Tantei Nougami Neuro"
You could also do Beyond Birthday or Near from Death Note, depending on what you have in your closet.
Lucy Heartfilia from "Fairy Tail"
Gray Fullbuster from 'Fairy Tail"
Kagome Higurashi from "Inuyasha"
Sai from "Majin Tantei Nougami Neuro"
Ed from "Cowboy Bebop"
Spike from "Cowboy Bebop"
Most of them depend on your closet and what you can get in a short period of time. But those are the ones I could think of that were relatively simple to put together.
EDIT: I second a Homestuck human character.