Internet Shopping (Ebay, Overstock, Etc...)

Internet shopping has been on a steady rise. With online retailers like Ebay and Overstock, I am beginning to wonder if the online shopping is actually hurting some retailers. As an avid shopper of Ebay, I know that a lot of things people buy can be found on Ebay for a lesser price. I have purchased everything from textbooks to tickets to Kenny Chesney. Do you think these online powerhouses are helping out economy or hurting it in the long run?