COUPONS.COM - this printable coupon site is by far the most popular due to the wide range of coupons that are available. Typically, you are able to print 2 coupons per computer, per month. Keep in mind that while there are print limits per computer, there is also an overall print limit - so if you see a coupon you think you would use, print it immediately. Printed coupons from this site generally expire 1 month to the date that you print.
RedPlum - this site features a big variety of grocery, cleaning, health & beauty items coupons on a regular basis.
SmartSource - this site includes many of the same coupons you would find in the Sunday SmartSource inserts. Grocery, cleaning supplies, health & beauty items coupons can all be found within this printable coupon site.
E-Centives - this site powers Target's printable coupons. You can print the manufacturer's coupons from this site without the Target logo.
SnackPicks - this site is sponsored by Kellogg's. This a a great site to find coupons for Kellogg's and Keebler products. Click on the "Coupons" tab - top right corner, then login to view current coupons.
BettyCrocker - this site is sponsored by General Mills. A wide range of coupons are often available.
EatBetterAmerica - this site is sponsored by General Mills. Available coupons often include GM cereals, cereal bars, health & beauty products and cleaning supplies. Login, then click on "Coupon" tab to view current coupons.
VeryBestBaking - this site is sponsored by Nestle. Features monthly coupons for Nestle products. Click on the "Promotions" tab on the left side of page to view current coupons.
Coupon Database - search for any coupon you may need to see if there is one available. Deal Seeking Mom has done a fantastic job of creating this database and keeping things up to date.