Sara Aronin and Michael O'Neal penned a great article in the Summer 2011 edition of Science Scope magazine entitled "Twenty Ways To Assess Students Using Technology". It provides a number of innovative ideas for ways students can demonstrate mastery of content in unique, authentic, engaging ways. Products that students create are embedded with critical 21st century skills that our students need to exercise on a daily basis in the classroom.
The 20th century was for teacher directed learning.
The 21st century is for student centered demonstrations of mastery.