You can actually get $10/mo DSL from AT&T. The speed is pretty basic @ 768Kbps down and 128Kbps up; acceptable for basic web browsing but not good for streaming movies, etc. to the big screen. AT&T is required to offer this price through 2009 as one of their concessions to the FCC relating to the Bell South takeover. A local AT&T phone line is required, long distance is not.
AT&T is NOT required to advertise this price however, and as such they make it hard to find & sign up for.
See more here, third promotion from bottom (“AT&T HIGH SPEED INTERNET BASIC PROMOTION”).