What do you use to learn a foriegn language?

Title says it all, really.
Have you used books? Classes? The Internet? Rosetta Stone? A combination of multiple sources?
Also, what have been your experiences with different language learning tools?
For example, this guy on youtube critiques the Assimil series  (http://www.youtube.com/watch?v=XLvTEqXqlsI&feature=channel_page).
Has anyone ever used this series and found it useful?


TLDR itt: tools you use/have used to learn a language and what you think of them.

Books. Classes.

I speak fluent English and I am an intermediate speaker of Japanese. German is my native language and I can read latin.

A lot of people hate classes but they really are great (especially in the beginning) if you dedicate yourself to study outside of class.  The key is not the let the class pace hold you back.

My common sense.
No, really, it's the most important and effective tool at your disposal.