A 33-volume collection of award-winning oneshots put out by Kodansha from 2002-2012. Some of these would later get serialized or collected in other volumes. Click here for the full list (.txt).

Serialized or otherwise collected:
AKABOSHI Tomo Shishunki Syndrome
AKIZUKI Risu Oku-sama Shinkaron
ARAI Hideki 8-gatsu no Hikari
ARAMAKI Keiko GENOMES
ASADA Torao Spoonman 3.18
ASHINANO Hitoshi Yokohama Kaidashi Kikou
Endo Hiroki Kitto Kawaii Onnanoko Dakara
ENOMOTO Shunji Golden Lucky
IGARASHI Daisuke Obayashi ga Hikoeru Hi, Hoka (collected in Hanashippanashi
IRIE Kiwa Haikibun! Sakanahime
IRIE Noriko Neko no Te Kashimasu
KIMURA Kon Koube Zaijuu
KITOH Mohiro Vandemieru no Tsubasa
KOMAI Yu Sonna Yatsua Inee!!
MATSUMOTO Taiyou STRAIGHT
NIHEI Tsutomu BLAME! (prototype chapter, included in NOiSE)
OHARA Shinji Boku wa Otouto
SAMURA Hiroaki Mugen no Juunin
SOUJI Hajime Sanmon Mirai no Katei Houmon
TOUME Kei Kurogane
TOYODA Minoru Love Roma
TSUCHIDA Seiki Miseinen
URUSHIBARA Yuki Mushishi prototype chapter, collected in Filament
WAKANA Shouhei Kamen Tenshi

Other:
Hiramatsu Kannosuke Yume

ABE Yoshitoshi Ame no Furu Basho
Eshikawa is a man who has lost sight of his life and stumbles through it, with no clear meaning or purpose. One day, he is informed that his ex-girlfriend committed suicide, which sets his brain on retrospect mode. He goes on a journey of self-revelation and contemplates upon the myriad of human emotions, the joys and sorrows of normalcy.

YAMAZAKI Ren Like a Laika
From Atelier du Noir Scans:
The daily, average life and interactions of some of a ship’s crew as they depart to explore space. Winner of the Jiro Tanaguchi Special Award for manga in the 2010 Four Seasons Award Anthology.

NADEGATA Nazuna Kokenoshima
From Atelier du Noir Scans:
On a remote island, a skilled swordsman who honed his craft on the local population attempts to atone for his sins and lift a curse by hunting and killing demons. Winner of the Hagio Moto Special Award for manga.

KIBA Kouichi Jagua
As the protagonist is returning home one night, she runs into a man who had just been in a car crash. As he is dying, he asks her to throw a certain package into the sea.

JOUYAMA Yui Zanuff the Butcher
A butcher with a dark secret finds a little girl.

HAYASHIDA Q Sofa-chan
Tells the story of a female ghost who lives on a couch and it's the debut work of Q Hayashida as mangaka.

KANOU Rie Kingdom of Stars
Oneshot about love, religion, and a big misunderstanding that leads to a weird situation...