r43 is the most stable of the projects that I need to give up. It implements nearly all of the 43 Things API (it doesn't handle the posting related methods), and has a comprehensive test suite (98.2% of the code is covered by the test suite according to rcov) — although I sometimes run into problems with methods in the API breaking on the server side.
A good first step for the new maintainer of r43 would be to audit the package against the 43 Things servers, and cut a 1.0 release. This could be followed with development of the posting functionality, and/or some general refactoring and the development of user level docs. At one point, we were going to develop some Rails tools to use r43, this could be a good project too.
Are you interested in taking on r43? Add a comment below telling me what you'd like to do with it. This could be a great introduction to managing a Free Software project for the right developer.