GameData for Achievements
I'm dreaming of a custom window to display your currently selected Achievement's requirements, much like the Active Quest window does for regular quests. There's no GameData for this information, though, and I'd love to see it implemented!
For instance, you visit your Achievements tab in your journal and select Exploration > Shattered Lands > Antonican Adventurer. The Achievement Helper window would be populated with that achievement's requirements -- in this case, the list of locations you have to visit.