A couple of things that should be somewhat simple to implement but really useful.
1. The ability to name mainline keys
Simple naming property to the key field with a hotkey + mouseclick text field modal or something could be really useful.
2. Invisible mainline range fields.
So, being able to add ranges to the timeline would be pretty awesome. Ranges wouldn't affect the animation at all but would rather serve as invisible markers on the timeline for either the artist or the developer.
When I say ranges I mean something like 2 (start,end) range markers on the timeline that would specify where an attack can actually cause collision f.e.
Keep up the good work and stuff.