Babbel
You know how there are some sites that are so very exciting that you have trouble stopping messing with them long enough to post about them? Well, this is one of those. Babbel is the latest in a long and checkered history of foreign language tutorials online. If you go back aways online, you may remember the thrill of the early online language dictionaries! Search a word and see it in 20 different languages.
Fast forward to the present and Babbel is one of the best FREE foreign language training sites I have ever seen online. The site is limited to teaching German, French, Italian and Spanish, but that is a plus. The focus allows them to create real quality teaching tools for people to use. The lessons are interactive, but not confusing. The emphasis is on the learning not the flash, but it is plenty flashy and nice. I found the interface intuitive, fun and engrossing. Just the sort of reaction you want to have when learning a language.
Give it a try! Then recommend it to your patrons!