I’ve posted about some of the BBC language sites before (particularly the Gaelic ones, if I recall correctly), but I just found the mainBBC Languages web site, and it’s pretty darned neat for learners of several different languages. They have lessons posted in several different levels, including audio and video content, and if you’ve previously studied French, German, Spanish, or Italian, you can take an online test to see which level you’ve achieved and which resources best suit your ability.
I passed all the questions in the German test (which might rank me a little more highly than I ought to be), and came in at the beginner level in French (which is about right), and the site recommended specific programs and exercises would be best for me. The programs and exercises are all available for free right there on the BBC site. It’s really a great resource.
Don’t forget to visit the “Other” section, where languages such as Greek, Gaelic (both Irish and Scottish versions), Welsh, and Chinese can be found, though I don’t believe there are ability assessment tests for those languages on the site.