I'm planning a trip for Summer '08 and will be in Helsinki for 3 days. Any suggestions or recommendations would be greatly appreciated!
Avoid Helsinki June 20-23; this is when the "mid-summer eve" holiday occurs. During this weekend absolutely everything will be closed: tourist attractions, stores, and restaurants. The city will be like a ghost town. As hotels go, you can get some very good deals at business class hotels during the summer months in Finland.
Look into the Helsinki Eurohostel. It is a Hostelling International hostel, close to the port with lots of single and double rooms. It has been a while since I stayed at this place so I cannot really remember details. However, hostels in Scandinavia are generally of good quality.
Don't miss the Church in the Rock. I thought this was really memorable.
I agree with Laura about the European hostel. It is on the trolley line and very clean.
Rooms are large. Very reasonable. I reserved a day in advance and stayed there twice before and after the ferry ride to Stockholm. They have a web page you can find by searching for helsinki hostels.
There are islands in front of the town that you can visit by a ferry. One is an old fortress from the 1700's and there is a zoo on another island. You can also take a ship to Porvoo, an old historic town for a day trip. Helsinki has nice outside cafe's to sit and people watch.
You are so right Isailtheseas! Plus I think Rick needs to get an update on Helsinki it has changed a lot since Finland joined the EU. I was shocked to see how much more cosmopolitan it seemed since my last visit there in the early 90's. There are several great museums: The National Museum near the Parliament House, The Sinebrycoff museum on Bulevard not far from Stockmann's, the University Museum next to the white Chatedral. Don't forget to take a leasurely walk through the indoor marketplace call Halli at the harbor and taste the local delicasies. Also you must not miss the bakery at the Stockmann department store. There is an amazing variety of top notch baked goods.