Preferably in C++, but code in all languages would be good to. Should be well categorized for different purposes, and have side by side comparisons.
To clarify what I'm looking for. Let's say I wanted to find a graphics library. I would search for that, and it would give me a list:
SDL OpenGL Ogre Allegro etc...
Each one would be rated by users and or professional reviewers, and some of the more popular ones would have written reviews.