This is the day that most of the coupons that are in newspapers are available (sometimes I'll find inserts in the Frankfort Times and the Lafayette J&C). I'm never sure ahead of time if I want to purchase a newspaper or not though (a lot of friends know I coupon and keep their inserts for me!).
So every week (usually on Thursday night) I venture over to couponclippers.com and check to see what might be in the upcoming Sunday paper.
If you click on their tracker link it takes it you to a calendar and on the Sunday dates are links to the Red Plum, Smart Source and P&G (first Sunday of the month usually). Click on those links and you can see what coupons will be in the inserts. Keep in mind that they do vary by region (here...Indy Star has better inserts than the J&C from Lafayette).
Also, coupons aren't in the papers on the Sunday after a holiday. So keep your money in your pocket!
I'm off to check out the inserts on The Coupon Clippers now. Good luck finding some good coupons!