Archive (aka zip) Input/output for Qt based on the QIODevice API.
Langadia++ 2 is a class library base on Qt 4. It seeks to provide useful tools especially for game development.
Langadia is a framework for Free Pascal using SDL, Lua and OpenGL.
Langadia++ is a platform independent framework based upon SDL, OpenGL.
RPdev Game Development Kit
The RPdev Game Development Kit (RP/GDK) is meant to be a collection of useful classes that are handy when writing games (and maybe other applications such as visualization apps). It is written using Qt 4.