Clojure atlas: hand curated ontology of clojure concepts [Announcement only]

That said, I think there's actually a sizable latent market for software development tools and "aids" (trying to get out of the mindset that dev tools == IDEs here) that people will pay money for. No, people won't pay for yet another Eclipse plugin; slightly better code completion isn't going to move a needle anywhere. Part of that is due to the commoditization of such dev tooling, but part is also due to a lot of developers coming to realize that, in many ways and in many contexts, "dev tools" as we've known them really aren't the panacea of productivity that they were once thought to be.

On the other hand, produce development aids that really do move the needle – provide insight, accelerated deep understanding, better planning and estimation, etc – and you might have something that is actually valuable, and therefore a commercial interest.