Storsjön is famous for being Sweden's Loch Ness and some even claim there is a secret passage to the Scottish lake. Whilst I don't doubt for one second that people have seen huge unidentified water creatures here, I think it might be because of the unique geology - some huge fish is known to thrive here for instance. Whatever the real truth, there is a legend about the monster being created by two witches who just stirred their pots with various ingredients. The town now lives on this legend and everywhere you go, you will see souvenir monsters - everything from cuddly toys (like the monster's son Birger!) to tasteful handicraft.
Being the capital, this is the place where you see more Jämtland flags than anywhere else as yes, this is a self proclaimed republic. Jämtland was Norwegian, then Swedish and all the time mostly independent in the "uncontrollable" highlands so there is a strong regional sense here and you will see the white, green and blue striped flag on many a porch. At the festival in July, a president is also elected and is someone who has done something good for Jämtland - usually amongst national celebrities.
Every late July, beer tents are created in the small harbour and stages built everywhere as the music and culture festival goes on for a week. The current Jämtland president (this is a very independent province) holds a speech and there is music and film galore. Less known Swedish bands along with world famous ones.