Basic Finnish lessons through games
Finnish Sound Structure: Phonetics, phonology, phonotactics and prosody
By Kari Suomi, Juhani Toivanen, and Riikka Ylitalo © 2008 University of Oulu, an advanced book (PDF) about Finnish pronunciation
User-created Finnish courses
Online short course by the University of Helsinki
Uusi kielemme — Finnish for Busy People
Grammar reference, extensive vocabulary lists, book recommendations.
VISK — Ison suomen kieliopin verkkoversio
Reference book for Finnish grammar (in Finnish) by Kotus, The Institute for the Languages of Finland.
Articles on the Finnish language, Finnish grammar, Finnish phonology, Finnish orthography, and colloquial Finnish.