In the world of online language learning, there are basically two heavyweights: Duolingo and Babbel. Duolingo is betting on a freemium model and a strong focus on using algorithms to help you learn better, while Berlin-based Babbel is a paid service that employs hundreds of teachers. As Babbel co-founder and CEO Markus Witte announced at TechCrunch Disrupt Berlin today, his company is now moving into a new area of language learning with the launch of a language travel marketplace.