Sven Bergström who is one of the main contributors to Lime, the low level library that powers OpenFL, has created and released hxcollision. It is a port of the Separating Axis Theorem, currently supporting polygons and circles. It only provides support for collision, no physics have been include, by design. The site provides a solid set of demos, examples, documentation and release notes.
Michel has created and released hxstd.vm which covers everything you know from the standard library, but unified under a single package allowing cross-platform usage of Mutex, Locks and Threads without any more conditional imports.
Michel then finishes off by creating bindings to nanomsg, which is a socket library that provides several common communication patterns that make networking fast, scalable and easy to use. The hxnn library can be used with the C++ and Neko compile targets.
And to finish up, you can now get the Haxe manual on your ebook, currently only
mobi formats are available.