oh yeah I visited "dansbandsveckan" as well.
Dansband ("dance band") is a Swedish term for a band that plays dansbandsmusik ("dance band music"). Dansbandsmusik is often danced to in pairs. Jitterbug and foxtrot music are often included in this category. The music is primarily inspired by swing, schlager, country, jazz, and rock. The main influence for rock-oriented bands is the rock music of the 1950s and 1960s.
It isn't really a festival but close enough!
http://www.youtube.com/watch?v=_NW-5nciW9o
one of the most famous dansbands songs ever!