A close-up of Heather’s back tattoo, from her MySpace.
Naya has another tattoo on her left ankle - a peace sign.
Lea got this butterfly tattoo on her lower back with her mom.
Another Heather tattoo on her lower hip.
Found!: a picture of Amber Riley’s tattoo. Thanks jaymcb!
Assuming that her tattoo faces upright when her arm is down, and that this picture was taken with a webcam (looks like a mirror effect to me), then the symbol seems to be the logo for Not Of This World (a Christian apparel store).