The Barnes & Noble Afffiliates program enables you to set up links on your website and earn an extra commission on sales of your books when customers follow the link to the B&N site.
The Amazon Associates program enables you to embed links on your website that send customers to the product pages for your books on the Amazon site, and earn a commission of up to 8.5% on sales that occur through your links.
Joining Kobo’s affiliate program is a great way to promote your ebooks in Kobo’s store, measure outbound visits to Kobo, and earn extra revenue from lead generation.
Apple has some useful tools that you can use to help promote the presence of your ebooks in Apple's iBooks. They're all free, and some of them can even...