I've played the Elder Scrolls series (starting from Morrowind) for almost a decade. Modding well over half of that. I also do modding work for a huge variety of other games, including RPGs, RTSs, simulation games, etc. Largely scripting, but I also take a crack at 3D when I feel like it. I typically do not release, but comment significantly and find bugs.
List of other modding projects that I at least have superficial involvement with in order of work involved:
