Add the documentation for Clearance to that list.
Blog posts and wikis are good for tutorials, not for API documentation.
YARD is awesome. Take five minutes to scan the Getting Started page.
rdoc.info is open source. I'm happy to outsource documentation generation and serving like any other service such as source code hosting or error notification tracking.
Positive side effect: visibility
The process of documenting with YARD made me think harder about public/private visibility. I was surprised that documentation could be a design tool.
Looking at the public API, I noticed how many methods are required to handle the remember me as a "feature".
If we go to a GitHub/Tumblr model, the API will be simpler and the implementation cleaner.