Brent Simmons (of NetNewsWire fame) has started a Yahoo Mailing List for independent Mac developers -- people who have started a Mac-related business, or who want to. I've joined the group, since I probably have some insight ... and questions to pose of others too.
Its charter/description:
This group is for small, independent Macintosh developers who want to talk with other developers about the business of Mac development. Questions on pricing, packaging, advertising, e-commerce providers, and so on are on-topic. Note that this list isn't a vehicle for promotion: announcements and press releases are off-topic.