I don't think the 70% growth pertains to digital text books...it relates to a bunch of other "services" like homework help, some pre-college community, and an internship site. Digital books is probably
Being a college student that works a job, researches and invests in stocks, studies and also finds time for a social life, I find their service very useful, one that I cannot find anywhere else.
In school nowadays they make us take classes we really don't need and assign us useless homeworks. I figure that my time is better spent in other places and so I got the service. The tutors literally do my homework and save me loads of valuable time. Just found out about their internship service and I will check it out.
I don't believe they will be able to compete in the hard textbook market since amazon offers lower prices and students have turned to pirating etextbooks, but I believe their online service does not have a formidable competitor. I would not be surprised to see a company like yahoo acquire CHGG and so I am long on the stock with calls I may decide to exercise before expiration. Take it from a college kid they have a great service that I would pay twice what I pay right now for.