Less altruistically, some businesses have discovered that Twitter is an effective way of communicating with consumers. Dell (NASDAQ: DELL) says Twitter has produced $1 million in revenue over the past year and a half through sale alerts. People who sign up to follow Dell on Twitter receive messages when discounted products are available the company's Home Outlet Store. They can click over to purchase the product or forward the information to others. Dell started experimenting with Twitter in March of 2007 after the South by Southwest conference, an annual tech/music festival in Austin, Texas. Conference attendees could keep tabs on each other via a stream of Twitter messages on 60-inch plasma screens set up in the conference hallways. There are now 65 Twitter groups on Dell.com, with 2,475 followers for the Dell Home Outlet Store.