People who "just" want to learn another language find themselves in a slightly better position. The web is full of "free" language courses, podcasts, flashcard systems and introductions to modern Navaho. However, closer scrutiny is required: although many sites come with a "free" badge, they are often only "free to use". Only a very few foreign language resources are truly "free" according to GPL, FDL or CC.
And for those who thought that open source is only available for Linux and BSD: this flashcard system for mobile phones only works with devices based on Windows Mobile. Another site for learning Russian goes even further and contains an English-Russian dictionary released under GPL for Windows XP with .NET only. This does give rise to the question why the Linux world releases about 200 Open Source httpd demons, while Mac and Windows programmers release utility software for everyday use.
Some things are harder to locate: really good, comprehensive vocabulary lists as we know them from books - "Basic and intermediate XYZ". Vocabulary lists, foreign language dictionaries equivalent to the Oxford English Dictionary or to Petit Roberts – no such luck. However, these word lists would be an essential basis for more free language projects.
At least there is the freedict project. The files are available in various formats: for dictd, TEI-compliant XML (the "official" DTD for marking vocabulary in XML) and already converted for StarDict. However, the quality of the free dictionaries does fluctuate: The German-French Freedict dictionary, for example, knows neither the translation of computer nor the term citoyen for citizen - not exactly the least popular of French terms. There are no words for feminine or masculine or references to verb conjugation or the plural forms of substantives.
So, all ye language enthusiasts who wish to contribute something really worthwhile: create good quality word lists - for flashcards, language courses and dictionaries - and make them freely available to all. (odi)