If you want to get a head start on your couponing, or if you just want to find out whether this Sunday's paper is going to be worth it to buy, check out the Sunday Coupon Preview!
This website is a great resource where they list what coupons are coming out this weekend in the various inserts. I use it to make my decision on whether I will be buying a paper each week or not (which I usually do unless there are no inserts).
Just remember, some coupons are regional, so you may not get everything listed. Also, be aware of what papers you're buying. Some local papers are not going to have as many coupons as larger papers. For instance here in Hagerstown, it makes a lot more sense to stock up on the Washington Post rather than the Herald Mail, because the Herald Mail only has a fraction of the coupons that the Post tends to have. Also make note of where you're buying papers. Convenience stores and gas stations tend to mark up papers much higher than grocery stores do.