Some of you might know this, others might not even care, but one of my private passions is a MMORPG game called "Asheron's Call" that Microsoft originally published with Turbine games.
Valorie started playing it first (she was an early playtester for it), and I got hooked when I put out my back several years ago.
It's been a long strange trip, AC is no longer published by Microsoft, it's now being published by Turbine directly, but the game's still pretty fun to play.
One of the reasons that AC is compelling (IMHO) is that Turbine has not discouraged 3rd parties from writing tools that enhance the gameplay experience of AC - there's an extremely rich infrastructure of tools that enable all sorts of interactions with the game beyond those that the designers anticpated (automating crafting interactions, auto-salvaging of loot, monster detection, etc). These plugins all run in a framework known as "decal".
Turbine recently released an expansion pack which rolled out an entirely new client (based on Turbines AC2/D&DO/LOTRO client). This has broken all the 3rd party applications that were built for AC, because of the massive infrastructure changes that were introduced.
Adam Wright (Asriel), one of the decal developers has been posting a fascinating series of articles that describe the process that the decal developers are going through to re-create the decal functionality on top of this new client. It's well worth reading, even if you don't care about playing AC.