This is interesting. I was going back and forth with Amy Hoy on twitter the other day about the trend (maybe I'm seeing one where there isn't) of doing a successful product or two and then turning around and "selling how you did it", which she's doing with a course, Rob Walling is doing with his micropreneur academy, and 37signals does it with their books.
I don't think there's anything wrong with that (indeed, I'm very happy with Rob's book and recommend it to people), but I'm also somehow glad to hear that you see more money and prospects in products than turning around and selling to people who want to emulate your success.
I think those are a couple different trajectories there. 37Signals/FogCreek both have modestly successful sidelines attached to massively successful software businesses. DHH is not going home at night thinking "Bwahaha, forget Basecamp, another book and I'll have to rent Lichtenstein to park my fleet of sports cars." Amy & Thomas have gone from consulting to info products to SaaS (concurrent with info products/training) and I will eat my hat if the SaaS doesn't eventually swallow the rest of their business because the economics of it are just so freaking compelling. I don't have a good guesstimate of Rob's numbers.
For my part, the trajectory was different: modestly successful product (and ancillary blogging/community participation) lead to lucrative consulting opportunities and gave me enough runway to do a SaaS which will probably eventually swallow any availability for consulting (like it did for 37Signals, FogCreek, etc).
I don't think there's anything wrong with that (indeed, I'm very happy with Rob's book and recommend it to people), but I'm also somehow glad to hear that you see more money and prospects in products than turning around and selling to people who want to emulate your success.