I was cleaning out my junk e-mail box today and for some reason I decided to read the one from Chewy.com. I was given a user-specific code for $15 off a $49 pet food order with free shipping. From my experience, Chewy.com (and Petflow) discounts are typically only for new customers.
I ordered a 30 lb bag of Taste of the Wild High Prairie ($44.89 - same as Amazon's price) and a Chuckit! Small Kick Fetch ($12.38 - same as Amazon) for a total of $42.27 ($44.89 + $12.38 - $15.00 = $42.27 with no shipping or tax for me). Not bad. Even though the e-mail said $15 off a $49 pet food order, the entire $49 spent does not have to be all food to qualify.
Not the slickest of all slick deals, but $15 off stuff I was already going to pay Amazon today $57.27 for is good enough for me.