M.L.
http://www.downeastbasics.com (cute everyday clothes)
http://www.shabbyapple.com (super modern and adorable dresses)
http://www.shadeclothing.com (cute everyday clothes and layering basics)
http://www.funkyfrum.com (their skirts are cute, not so much anything else)
Most stores have modest clothes... if you don't mind layering. I wear tank tops a lot under shirts that are usually way too low cut or cute little cardigans over sleeveless shirts. Old Navy, Gap, Kohls, JC Pennies, Abercrombie, American Eagle, J.Crew stores like that tend to have lots of modest tees and such.