The Mac OS X forum is for discussing Mac OS X itself, not the things that run on it or connect to it.
Any standard PPP ISP (that is, NOT an "online service" like AOL/CompuServe) will work fine on Macs, provided that they don't require the use of a proprietary dialer to set up the account initially. As far as non-discount ISPs go, Earthlink is a good choice.
tooki