In Sweden:
Weather permitting, these dropzones operate during the winter. I think all of them are weekends only this time of year. I'd recommend you dropping them an email before you arrive, to make shure they operate that day.
Closest to Stockholm and Arlanda Airport: http://www.fkaros.se
Largest city on the westcoast: http://www.hoppafallskarm.nu
Other smaller places: http://www.afsk.se, http://www.ofkdz.nu and http://www.ofsk.net
Have fun and Welcome!