Chicago, Illinois (USA) based ShareASale.com is an affiliate marketing network which allows you to sign up for merchant affiliate programs that pay out on a per sale, per lead and/or per hit commission depending upon the merchant. Once accepted to a merchant’s affiliate program you’ll be able to grab code to insert links and banners to that merchant’s site. Also, some merchants have made “data feeds” available which allows you to grab their entire product catalog to import to your own site and create product specific links.
One word of advice regarding signing up for affiliate programs: make sure that the merchant is relevant to your blog audience. While there may be merchants that interest you personally, the focus of selecting merchants should be your blog visitors since they’re the ones who will be generating clicks and sales.