A timeline UI would be huge for animation / interaction design. Timeline A/V effects (Seriously.js) could be built with flows, timelines could trigger flows, flow events could trigger timelines....
The state of Interaction Design tools by Pasquale D’Silva argues that there is a hole in current tools, and there needs to be a connection between code, flow, and timeline. Apple is rumored to be updating QC with a timeline-centic view, but it's Apple, so you know it won't be webby.
ui animation building
interactive music videos
trippy gif generators
The way that I see this working is a noflo-timeline component that is connected (somehow?) to a noflo-ui timeline widget. The component would be minimal, sending out tween values as needed.