This is an idea I had a few years ago and which has become popular today. Since language is not only a question of words but of culture we decided to mix the students who came to Santander to learn Spanish with our students at the school of languages. And that's how everything started.
We hold three parties every summer. After 10 years we have registered at least 2500 f2f language and culture exchanges. This means people meet after their lessons and help each other to practise the language they are learning. As far as I know the "que tal language exchange parties" were the first international students' cafes to be organised by Universities. They started even before the Comenius students exchange programme!