Dconf "joker seminars"

[IGotD-]

The Joker is a card that doesn't really belong to the regular 
deck of cards. Another term would be "guest seminar". The point 
of such seminar is to invite a person who is working with another 
language than D and can explain how things works and are 
different from D. This can serve as inspiration for future D 
direction as well as encouragement to learn and investigate other 
languages. Any serious software engineer should really dwell into 
several programming languages.

It doesn't need to be a language but also a library that perhaps 
isn't available for D, among other things. Preferably it should 
be an outsider, so that the person isn't biased to much towards D.

This is similar to how I've seen Ali Çehreli do D seminars in a 
conference dedicated to C++. No one seems to mind and think that 
his seminar are interesting and also can give C++ programmers 
another perspective.

I was thinking, shouldn't we have a goal to have at least one 
joker seminar each Dconf?
Have Dconf invited outsiders before?
Do you think this is a good idea?