"Wild Card" by Leah BobetIt's at Amazon.com, Barnes & Noble, and Smashwords now, and will soon make its way to all fine booksellers.
"Underworld" by Elizabeth Bear
"Single Bullet Theory" by Chelsea Polk
"Apolysis" by Emma Bull and Will Shetterly
Plus two short extras!
Haven't tried Shadow Unit yet? The first volume is still free at Amazon and Smashwords.