Here is another one to keep an eye on:
http://www.juiceboosted.com/
JUICE Free Broadband speed over dialup

There have been some interesting discussions
about this on the Warriors Forum.

From their FAQ pages:

The JUICE service carries no identifiable means of revenue to JUICE itself and
certainly not enough of a revenue stream to fund paying affiliate's commission.
JUICE will make Internet life much nicer for users, however hidden away
invisibly in the service are hundreds of thousands of "points of revenue" that
JUICE has affiliated themselves with that generate them a huge revenue. It's a
WIN-WIN situation where, as you make money so do we.