On clark howard's website, there is information on AT&T "naked DSL" for $10 per month. Bellsouth has one for $19 per month. No home phone service, just DSL only. It is designed for those using cell phones for phone service.
Netzero maybe free, but it will actually connect at about 22kb per second and half your video screen will be filled with advertising.
AOL still allows dialup also, and has closer to 56k speeds, but takes a long time to initially load each time you dialup.
Compuserve is still around and still allows dialup access, approx $17 per month.