The bin and group transform could propagate the title channel, if any, by default

[mbostock]

E.g.,

Plot.rectY(data, Plot.binX({y: "sum"}, {x: "date", y: "count", fill: "name", title: "name"}))

would be equivalent to

Plot.rectY(data, Plot.binX({y: "sum", title: "first"}, {x: "date", y: "count", fill: "name", title: "name"}))

And possibly it could even be smart by showing the distinct values rather than just the first? Or it could be like Fred (42) and show both the distinct values and their respective counts by default? I feel like that would be very useful.