Introduction
It was way too early to be writing this, and I feel like I missed some very common tradition(s)... Please feel free to post if you know other popular ways of celebrating the new year, and I'll add 'em here.
The New Year's Eve here is a celebration of the upcoming next year. There aren't many special traditions for this day that I'd see as Finnish, but more or less universal ways of welcoming the new year. Since the New Year has never been a religious event among the church, it is merely a 'reason' to get drunk and celebrate, since the next day (January 1st) is a holiday.
There is fireworks in each town at midnight. In addition, Finns use insanely big sums of money to buy smaller fireworks for home use. Some fire them on home yards or at parks, but stupid (drunken) teens shoot eachother (and innocent bypassers) with their Roman Candles in town squares and streets. There is a lot of debate about the misuse of fireworks every year, but it hasn't really changed in any direction in the past 20 years or so...
People melt tin to see what the next year brings to them. You can buy horse shoe shaped tin pieces from stores and on new year's Eve you put them on a small frying pan like metal spoon on a stove. After the tin has melted in the spoon, you pour the liquid into a bucket full of cold water and the tin becoms solid again. When you pick it up, you can predict your future from the shape and structure of the piece of tin. Some even cast the shadow of the piece to a wall and predict from the shapes of the shadow when you turn the piece around in your hand. For example, if the shadow looks like a plane it means you will go travelling. And lots of scribbly surface on your tin means lots of money next year.