After I finished my first book, I started to think about what I'd write if I did another one. I wouldn't write anything if it wasn't something I was interested in, so it had to be relevant to my interests. I discussed a book with a couple of publishers that was based around the end-to-end creation of a significant ASP.NET application, namely POP Forums. At the time, v8 wasn't much more than a idea (and still is hardly where it needs to be), so it seemed like a good idea at the time.
Most of the publishers I pitched to felt it sounded like a fairly good idea, provided it was well developed and easy to position as unique. I never really followed up on it though, but it's still something I've been thinking about in the back of my mind.
Truth be told, I'm not sure if I'd write the book for mainstream publishing now. I guess it depends on how well my first book did the latter part of 2005 (the publishing process is insanely slow when it comes to calculating royalties and such). It got off to a slow start, and I don't think it got much better after that. That's a real disappointment, and I partially blame the publisher for doing a really crappy job marketing it.
And while thinking a lot about POP Forums lately (especially the part about how I used to make a grand a month selling the really crappy old ASP version), I started to wonder if there was some way that I could monetize it a little. Remember, my motivation for writing the forum app is to use it in my own projects. I give it away only because I can't really sell it with all of the free stuff out there. But still, it would be nice to get something for that work.
I was looking at the stats from the forums site, which honestly has been more or less static for, I dunno, nearly two years, and people really like poking around the class documentation. They also make a lot of hits to the integration help page. And with the next version doing Membership/Profile, that's going to be even easier.
So thinking about all of these, I think a book on the forums would be a good idea, if self-published on something like LuLu. I don't need to sell 10,000 copies the way I would through a traditional publisher. I'd be happy to do 500 copies in a year. That would be something like a 2-5% conversion rate though from downloads, so who knows if that would be realistic.
I don't know... at this point I'm just kind of thinking out loud.
To me, as a developer, the book I was looking for, and couldn't find, is one on implementing AJAX and ASP.NET. Sure, Microsoft is coming out with ATLAS which should do the trick, but there will still be a rather substantial learning curve involved in transistioning to the "new" way of doing web-based applications.
You would probabaly have a greater market if you did a book like you said above, but add web 2.0 ideas (I know, you hate that term as do I) integrating with .NET.