Printable resources:
Coupons.com
RedPlum
Printed resources:
All You magazine, available only by subscription or through Wal-Mart stores. Has high dollar coupons each month (normally between $50 - $100 worth)
Trading resources:
Trading coupons that you don't want or won't use for coupons you'd like is an excellent way to help save money.
Coupon Forum
Organic Grocery Deals
Thrifty Fun
We Use Coupons
Coupon Mom