At some point I left a cushy full-time position for a consulting (in another area, to boot). Classic MBA education is obviously too heavy weight for me. All the things that I needed to run my one-man business I learned from a mish-mash of other consultants' war stories, web forums, and few books.
I would say that Fred Wilson's MBA series (http://www.avc.com/a_vc/mba-mondays/) or courses like Entrepreneurship 101 (http://www.marsdd.com/event_series/entrepreneurship-101/) are getting pretty close to what I need, but sometimes I need to know things that are even more down to Earth. Sometimes they are just technicalities, but very important technicalities: nevertheless. E.g.: how to choose corporate structure, what documents to keep for audit, does CRA (or IRA) accept scanned images instead of paper receipts, basics of accounting to make sure I work more effectively with my accountant, templates for invoices and shareholder meeting minutes, etc. Moreover, it would be great if such education was split into courses or stages. E.g. once my business grows large enough, I will want to know about hiring people, choosing and using CRM, setting up basic IT infrastructure. It is not that (if and when I grow) I am going to do all that myself, but I need to understand at least certain things at certain stages to make informed decisions and give more or less informed "go aheads" to people I hire.
I would definitely subscribe for something like this.