There's an infrequent but noticeable trend to use the d20 tag on questions about dice or critical hits or the like, despite the tag being clearly labelled as specific to the d20 System:
The d20 system, developed alongside D&D 3e, forms the mechanical backbone for a variety of RPG's entirely departed from the D&D system.
If the tag itself were d20-system, I think this would quickly and easily make the mis-tagging go away.
I know it's not a major issue in the grand scheme of things, but it's been bugging me so I brought it here. (I'm also curious why the tag wasn't "-system" in the first place.)