In addition to the Sunday paper coupon inserts, there are several great websites to print more coupons from (especially if you are building up your coupon supply). Some sites my require you to register in order to print the coupons. Also, make sure you check your favorite Grocery Store's website for even more savings. You can get some awesome extra savings on some of the items on sale in the store for that week. Target has great printable coupons that you can stack with the manufacturers coupons to get extra savings.
http://www.pgesaver.com/ - Proctor and Gamble Products