I've just got to level 6 in Spanish. And I'm starting French, in preparation for the summer holiday. It's very easy, and fun, but you need to practice, practice, practice to improve.
I'm talking about duolingo.com, the new website from the creators of re-captcha. Captcha is the annoyingly obscure set of words you have to re-type in order to prove you're not a robot, and the "re-captcha" version makes you transpose old printed books as you go. Duolingo works in a similar way, in that part of the learning process is translating texts from languages you're learning into your native language.
Duolingo's strength is in numbers, and it requires lots of users to translate the same sentences in order to reach a conclusion about how good the translation is.
What I've noticed is that many translators don't seem to be native English speakers (you can see and rate other people's translations) but presumably that gets ironed out in time.
The overwhelming impression I get is that duolingo is fun.. it's easy to practice and learn; you do it in short bursts and you can see your progress displayed as a nice graphic.
So if you're going on a French, Spanish or German holiday in the near future (other languages will be added), give it a go!