A top site for free printable coupons is Coupons.com, which allows the selection of coupons in several categories from a drop-down menu. This site offers coupons for many grocery types, as well as for items such as automotive and pet products.
Scroll through one or all available coupon categories on Coupons.com, and after "clipping" the desired coupons, print them off all at once.
Lozo.com is another website that offers free printable coupons. This source searches through hundreds of websites to show numerous coupons separated into categories. Lozo.com also allows narrowing the search according to brand, as well as by the type of software required for printing.