[neffy]

I do the same in my classes, and it´s common practice in many courses my dept which may help, as the students know what is expected of them. I don´t think it's wasting time. It motivates the students to know that they have to present in front of their peers, helps the shy ones get practice, and yes the quality varies, but it´s a very good way to share information within the class about different projects, even with a not so good presentation.