I use Amazon affiliate links on my blogs when I refer people to products. The redirector is there as it is much easier for me to link to /?XXXXXXX when I compile posts, than manually build links from the Amazon Associates site. From the disclosure on the site:

"Some of the links contained within this site have my referral id, which provides me with a small commission for each sale. Think of it as a form of tipping for the large investment of time I put into this site. Thank you for your support."