Electronic books are mainly available from Dawsonera (these are purchased ebooks or ones for preview/rental), plus other e-book websites:

Alex Catalogue of Electronic TextsA collection of public domain documents from American and English literature as well as Western philosophy.
BookBoonFree books available for students to download in PDF format.
Classic BookshelfClassic books in electronic format, with an option to customise page and font.
The Complete Works of William ShakespeareThe poetry will be included at a later date.
Dawsonera Dawsonera reading list ebooks, plus a 5-minute preview of other ebooks. You will need to log in with your User ID and password to access Dawsonera from off campus.
Ebsco DiscoveryeBook Collection (EBSCOhost).
Project Gutenberg The oldest publisher of free e-books on the Internet.
Online Economics TextbooksPublished by the Economics Department of the State University of New York (SUNY), Oswego.