I do occasionally run across free coupons and they are almost all from online offers. I have blogged about Kraft First Taste before where I manage to get several free coupons. Just sign up and check your account once a week to see what they are offering. Facebook is a gold mine for free coupons. Many companies offer free product coupons just for you joining their fan page. I find out about all these offers by checking out Hip2Save daily. This doesn't take long, I can scroll through all the offers of the day within a minute or two to see if there is something that interests me.
Finding a high value coupon in the paper and saving it to combine with a sale can net you free or almost free things as well.