[tokenadult]

Chinese (various Sinitic languages, but especially Modern Standard Chinese), German, Japanese, Russian, the original languages of the Bible, samplings of Latin and of various Romance languages, interesting conlangs, and others.

Here's a link to language-learning advice:

http://learninfreedom.org/languagebooks.html

Here's one of my favorite links about one conlang:

http://www.xibalba.demon.co.uk/jbr/ranto/

[wisty]

Chinese too. I've found Mnemosyne (a flash card app) quite useful, for learning lots of characters, though I already knew a lot about radicals, and how to combine them.

My personal project (not working yet) is a language learning web app. I think there's actually a couple of more advanced language web apps by HNers too.

[mattm]

Check out Remembering the Hanzi by Heisig