To build on the topic of ‘fun versus knowledge’, here is a worthwhile read about motivation by Adam Boxer. Ideas and examples from research are digested in a clear and logical overview which brings the reader to a very important conclusion: if you want students to be interested in your subject, help them become competent in it.
P.S. Compare it to Carl Hendrik’s post about ‘the dark side’ of motivational gambits in the classroom (I linked to it here): very similar thoughts!