I'm developing a library that allows you to have C++ mixins (vaguely similar to Ruby's mixins or the traits in Smalltalk's dialect Self and not to be confused with CRTP mixins).
It's not strictly about game development, but it can be treated as an alternative to an entity-component system, which is very useful for games with fairly complex objects (RPG's, Strategies).
The library has a lot of working and a lot of planned features, but for now I'm focusing on the documentation (which is pretty thin). I don't intend to add any of the planned features until I submit it to Boost.
Anyway I'd be happy to hear any comments, suggestions, and questions you might have.
Here's the link: https://github.com/iboB/boost.mixin (the name is Boost.Mixin, because I want to submit it to the Boost libraries for inclusion, but it's not part of them yet)