"Out of curiosity comes everything."
Learn Spanish resource pack
Free online courses at MIT & Stanford
Khan Academy
There are no formal teachers or lessons on MyLanguageExchange.com rather, it is a site for finding and joining up in voice chats (intermediate fluency in the language required), email pen-pals (great for beginners), and text chat (good for all levels).
You can use the free membership and use all of the features, you just can't initiate contact with anyone (they have to invite you). Gold membership allow you to initiate contact with other members for pen-pals, chat and more. Gold membership (as of Nov 2011) is $6 for one month, $12 for three months, and $24 for a one-year membership.
The club library is a collection of the public notes from all of our members' notepads. As members learn new vocabulary, slang and expressions during language exchange practice, they may record them in their own member's notepad. They can choose to share each note by marking it public. The library requires membership for access(but the free membership will work).
They also provide lesson plans for live voice chat sessions (usually 2-4 people) to guide the review and conversations making it easy.
If you've used this service, I'd love to hear from you on how you liked it and how it helped you most.