Lightpack is a cross platform ambient lighting program I came across while researching writing an almost identical program.
Main site with most upto date code (Russian)
http://code.google.com/p/lightpack/English translated version but older code
http://code.google.com/p/light-pack/While looking through the source code noticed that the author recently added Adalight support, so I made a local clone, compiled and tested. It does indeed work right out the box.
Why do we care?
It compiles cross platform using QT for the Gui.
It is written in C++ and compiles to a binary, from my tests it runs significantly faster than the Adalight processing code, but not yet quite as fast as Boblight (it is on the todo list).
Support for DX9 games under windows (DX9+ and OpenGL on todo list)
It comes with an API which supports other languages, Python, .Net possibly Java and Processing (Also includes examples).
Support for multiple profiles and quick switching between them.
It has a nice shiny icon and gui.
Modular code, so should be easy to extend.
At this time the released binaries do not contain the Adalight code, so if you want to play, head over to the Russian page, make a local clone of the repository (use commandline Mercurial or TortoiseHg on Windows and avoid making a Cloned Google Code project until you intend to contribute back code.)
The code, comments, readmes, compilation and installation instructions are all in English and fairly straight forward. The program its self defaults to the OS language. A debug build is slightly slower than a release build, but significantly larger due to the debug QT libs, so unless you are profiling for performance improvements you probably want to make a release build, which is easiest done from inside the QT Creator.
Remember this is not released code, so you will probably find some bugs, for example my current build sometimes crashes when I change profile.
If you are unable to compile a working binary, don't worry, I'm sure there will be a released build soon.
Since this is so close to the software I was intending to write, I will instead be trying to contribute back as many useful features as possible, however it does look like most of my ideas are already a work in progress on at least one of the branches.