The correct word is...
eBook
New to eBooks.com? <--- ebooks.com
WHAT'S HOT IN eBOOKS <--- booksamillion.com/ebooks
eBooks: Romance, Mystery: eBook store: <---
www.booksonboard.com
eBook Readers - eBook Readers & Accessories <--- Amazon.com
Harlequin eBook Store <--- ebooks.eharlequin.com
Sample eBook Library <--- adobe.com
eBook Readers <-- ectaco.com
eBook Search - Free Books for iBooks and other eBook readers <--- itunes.apple.com
eBook Free eBooks:: Reader Store <--- ebookstore.sony.com
Top 50 eBooks <--- kobobooks.com
NOOK Book (eBook) <--- barnesandnoble.com
Need I go on? I think not.