Stockholm's startup community has really blossomed in recent years. I think two reasons behind it are:
1. A more competitive tax policy (http://forumblog.org/2014/06/europes-top-ten-competitive-eco...).
2. More VC and Angel captial available as a result of previous Swedish unicorns such as Skype, Spotify and King.
If you happen to visit Stockholm you should check out STHLM Tech Meetup (http://www.meetup.com/STHLM-Tech-Meetup/) and SUP46: http://sup46.com/.