I know, if you are an expat and in Finland during Christmas time, it can get preeeeetty lonely. We Finns like to stick with our families, u know. You go to Facebook, no one's online. You go out, no one's there. It's lonely. I've heard there are some bars open in Helsinki and actually nowadays more and more people skip family Christmas because of broken family relations.
Like here in Berlin I have many Finnish friends who are not going home for Christmas. I'm one of them. I don't like Christmas - I don't understand why the whole family should pretend that it's nice to be together because rest of the year we're not having good flow.
Sources tell me that these bars are open Christmas evening:
Siltanen, Bar Loose, ... ok, rest of the bars I'm not even writing here because they are so horrible shitholes.
Actually I think that even my favorite bar, Om'Pu is open. And yes it is, and there's even Dj playing. Go to Om'Pu, it's always great fun there!