Why don't you combine those two - learning for fun and learning for examinations? Collaborative projects are a great way. Pen-pals/e-pals are very helpful. They enable our students improve all the aspects of their knowledge of English. 

My students are very successful in passing the Cambridge ESOL exams (from Starters to the CAE) and we've been using many projects in our teaching. Through these projects they learnt a lot of collocations, new grammar strucutures and improved their vocabulary. Our 13-17 year olds went on Skype with their peers from the USA so it helped them improve their speaking. And the most important thing is, they've all got their monitored e-mail accounts and each of them has got an e-pal friend. Try this. You might be surprised how well it works :).

Mirjana

Motivation that is what students need. As an English teacher, I notice that many students in my country don't have motiviation in learning English even though curriculum fulls of songs and games. In my point of view, motiviating students doesn't depend on what do you use. It depends on how do you use and how do you treat the students.