• Spoken Wikipedia exists in many languages
• The Arabic keyboard Service also allows internet users to enter characters from the Arab langne without having a physical keyboard this service (keyboard in Arabic) also allows for the translation from Arabic to several languages and vice versa
• BabelFish Instant Translation plugin for Firefox. Uses proprietary web services to actually do the translation, but it provides a good interface for looking up words from a web page. Maybe some day we can provide our own translation web service, whether it is edited by humans or assembled as a result of machine learning. (Actually, building such services is probably beyond the scope of Wikiotics, but it would be nice if they existed anyway.) 
• Foreign Service Language Classes Has many language lessons developed by the US Government, and thus in the public domain. These are full introductory circuli for many languages.
• If you want to learn the arabic language you can use this online virtual arabic keyboard to learn to type in Arabic with English/French letters.
• A firefox plugin for an arabic virtual keyboard for learning to type arabic via transliteration
• http://translatewiki.net/ is the translation effort for MediaWiki
• Tatoeba “At its core, Tatoeba is a large database of example sentences translated into several languages. But as a whole, it is much more than that.”
• Anki is a free software flashcard system.
• Mnemosyne is a free software flashcard system.
• How to Learn a Language and Language education wikibooks
• LanguageGuide.org
• Language Learning Reddit (see all-time top posts)
• Learn Any Language (Wikia), a community which also provides the #learnanylanguage IRC channel on FreeNode
• UniLang
• RhinoSpike allows people to submit exchange audio recordings of texts. The content is freely licensed.
• Språkskap
• FreeRice offers several learning games, including an English vocabulary trainer that adapts to the level of the user and some very basic vocabulary trainers in a few other languages