Cut out shoulders are the huge trend right now.
But instead of spending $$$ on a pre-cut/hemmed shirt, just grab some scissors and do it yourself.
Fold the shirt in half so the shoulders and arms are matched up very well. Make sure your scissors are extremely sharp to cut through what will be 4 layers of fabric (jersey knit is prolly the easiest). Draw on how big you want your cut out in chalk or just free hand it (like I usually do). Cut less first because remember, it's easier to cut more fabric away than add it.
courtesy of: David Learner Basic Black Tee from Swirl.com