As educators, we spend our time creating and sourcing relevant content. Some of us even go so far as to write our own publications. Here is a fantastic website that allows you to publish your own work and then have it made available on numerous sites such as:
OverDrive - this way your students (if your school has an OverDrive account) can take your book out of the school digital library

Now more than ever, it is possible to write and publish your own work. Visit: SmashWords