Interesting. I've been throwing around the idea of roughly the same thing for myself. I was keeping a TiddlyWiki, but that's stopped working. Developer solution ... write my own!
In general, developers are a terrible market because they think they can do whatever you did better / cheaper / faster, and they won't shut up about it.
I would say that developer tools are a terrible market for that reason. Information products (screencasts, books, etc) can be extremely successful in the same market. Examples abound, including patio11's marketing training[1], egghead.io[2] for AngularJS training, Peepcode[3], Railscasts[4], and various other ebooks [5][6][7].
Most developers that I know have two common traits that make info products an easier sell. First, they're innately curious about their field. Second, they have access to a company credit card that will happily pay for training materials.
In general, developers are a terrible market because they think they can do whatever you did better / cheaper / faster, and they won't shut up about it.