[Wikimedia-l] Leaving the Wikimedia Foundation, staying on the wikis
As I said earlier “Looks like you found yourself another worthy and inspiring endeavour. The project is huge in ambition, resources and time scale. BTW this is the first mission statement I’ve seen that sets its targets for 2100 😉“
Your first post to our mailing lists was almost (to the month) 10 years ago, about this project of yours: WikiTracer. I remember being much impressed about this project, which aimed to expand analytics to the wider wikiverse. WikiTracer brought a uniform scheme and layout, somehow overcoming the countless discrepancies between the wikis under study. Not the least of those challenges being babylonical confusion (on syntax, that is). Not long thereafter we spoke at length about your project, and mine, and how we shared other interests, among those Leiden and photography. The domain name wikitracer has since been reoccupied. You must have been too ‘distracted’ by this new mission of yours 😉
Your first visualization that focussed on Wikipedia solely (that I know of) was Notabilia. This was published roughly a year later, in 2010, and still exists, is still relevant, is still visually stunning, and represents my first introduction to d3, which I also came to love over the years.
When my wife Carolina and I started our new project, an OSM based tree map of Leidens park Groenesteeg, I remembered ‘Dead Letters’, your detailed photo-study of typography, showing graves in that very park. Your expo is now featured as one more layer of awesomeness in our tribute to urban nature 
I came to know you as (expanding on your own bio here) a [+very caring and sociable] ‘social computing researcher’ and [+very knowledgeable] ‘open knowledge advocate’ and just an overall very friendly guy. So once more: THANK YOU for the years we worked together, which I found most pleasant and constructive. I hope we meet again.