Here are a few good websites for those who learn Finnish.
http://www.connexor.com/demo/tagger/ : Morphology tagger. Doesn't necessarily tell you what everything means; you're on your own with that one. However, it takes any regular sentence (in a variety of languages, not just Finnish) and gives the part of speech and its base form. Quite useful when you get words like vesi in partitive, vettä, and you're not quite sure what the original word is to look up in the dictionary.
Although I don't use this one personally, as MOT Sanakirja (only accessible through university computers; if you are attending HY it's http://www.helsinki.fi/kirjastot/ and then MOT-Sanakirja) is far better:
http://www.tracetech.net/sanat
It does have a lot of words, so you won't be lost for not having a word. My only problem with it is that it doesn't necessarily tell you WHICH word is appropriate to the circumstance.
http://efe.scape.net/ is also a possible good one.
I have a fair number of other sources, and if you live in Helsinki, I can give you a lot of sheets which have nice systematic explanations on things.
Don
Good websites for learning Finnish
http://www.finnishschool.com is my personal favorite. 