I'm often left concerned when I feel students don't have enough opportunities to speak because the focus shifts from speaking to studying grammar, etc. While it's certainly necessary to study grammar & augment one's vocabulary, I've always thought Skype sessions are best utilized for improving one's conversational skills, i.e., for applying the lessons learned from books.
With this in mind I'm introducing 3 30-minute courses which aim to provide students the chance to express themselves at length in a more relaxed manner, without much need for preparation.