You can build your own widgets in Freeboard, and once completed, users can share new widgets directly with each other through GitHub. We are looking to build a marketplace of sorts as well, populated by the community, and curated for convenience.
I'm fairly sure that the actual data is unimportant if the widgets and data format are sufficiently generalised.
The important parts for me are how style-able the widgets are... seems like everyone is going for these carbon-black dashboards which isn't ideal for most of where we want to show it (ie, not a statusboard on a TV)