I am not sure how urgent you are but we are heading home in late October for 6 months and have a flat in a really old part of södermalm. so we will be looking at getting somebody to sublease it until we come back. we are more than likely to go through
www.bostaddirekt.se but we would much rather rent to help another kiwi out than through that website.
let me know if you think that it could work for you and maybe we can arrange a meet up:)