A Full Cup is where I go for my printable coupons. Under the 'coupons' tab, if you click 'printable coupons' it takes you to a database of most of the known printable coupons and links you to them. Under the same tab, you can also access printables from Smart Source, Coupons.com, and Red Plum. AFC has many other great features: A comprehensive coupon database, forums, blog lists, and a tool box where you can organize your coupons.
RetailMeNot is a site where people can put up coupon codes for websites, as well as printable coupon links for stores. Before I make any purchases online i always check retailmenot to see if I can save any extra money. Once on the site just type in the website/store you're looking for and it will bring up a list of everything that have for it. Users can also rate codes/coupons as to whether they were successful at using them or not.
Living Rich With Coupons is a great blog for people up north. Cindy posts deals and match-ups for ShopRite, Pathmark, CVS, and Walgreens. She also has great info for beginners and links to coupons where you can print coupons.
This page on BeCentsable lists grocery stores around the country and links you to blogs that cover those stores. Most likely you'll be able to find something in your are to help you out!
There are many more sites out there, so these are just a few to get you started. Are there others that you use? Please share with me!