there will always be something happening at Skansen http://www.skansen.se/ but it will probably be quite touristy

this organization is the central one for music, dance, crafts and costume http://en.wikipedia.org/wiki/Svenska_Folkdansringen

There is a competition for the "National Folk Musician" of Sweden conducted in a different place each year. The entrants are awarded the Zorn Medal if the judges agree that they play Swedish music in the traditional way. this event is a gathering of the best musicians in Sweden. The highest honor is http://en.wikipedia.org/wiki/Riksspelman reserved for those who win the silver or gold medal and the title of Riksspelman, http://en.wikipedia.org/wiki/Zorn_Badge

as near as I can tell, this Zornmärkesuppspelningar
event will take place in Örebro on June 27 next year 2011-06-27.
http://www.olfm.se/ http://www.orebro.se/1340.html