MetaMod is a plugin/DLL manager that sits between the Half-Life Engine and an HL Game mod, allowing the dynamic loading/unloading of mod-like DLL plugins to add functionality to the HL server or game mod.
QMM (Q3 MultiMod) is a pluginmanager for Quake 3 that sits between the Q3 engine and the actual game mod to allow pseudo-mods to be dynamically loaded adding new functionality to a Quake 3 Mod. Similar to MetaMod for HalfLife.
Moving to Github (https://github.com/thecybermind/qmm2)