Enter to win Blush, the topless undershirt, at Shop Annies. Basically, this is a band of lycra fabric that peeks out from beneath your overshirt, so that when you bend over or raise your arms, your skin is covered. I've used and loved a similar product during pregnancy.
http://shopannies.blogspot.com/2009/03/blush-topless-undershirt-giveaway.html