As we’ve been spending time getting to know the deals/shopping space, it’s become clear that sticking deals on a page is not sufficient. You need to provide users with a reason to come back to your site. If you have to keep acquiring customers for the first time, every time you want them to visit, you’re going to have a problem. Arbitrage margins are narrowing and that trend is unlikely to reverse itself anytime soon. There are some great posts on this topic at Bronte Media and Jellyfish’s blog.