Group buying deal websites have been around for a long time. Not satisfied with the current ones on the market? You can always build your own. DealPress for WordPress is a commercial theme that turns your website into a daily deals portal. Deals are treated as a custom post type. You can use PayPal and other payment gateways to get started.
DealPress is Facebook/Twitter friendly. It lets you maintain a side blog. The theme also supports Google Maps. Your users get e-mail notifications when their deals are purchased. DealPress is mobile friendly. The bad news? It seems the theme hasn’t been updated in a while.