We have used craigslist and freecycle for free stuff and had mixed results. Some good finds, others were not what the ads implied.
Here is a novel concept we will share with all of you. This is extremely hit and miss and some folks get down right nasty with your offer, but what the heck, you will probably never see them again.
When visiting yard sales, make a small purchase and offer to the folks running the yard sale that if they have anything left after the yrad sale is over, you will be glad to pick it up and dispose of it for them. Give them a personal card with your name and phone number on it and ask them to call you.
Many people will just want to get rid of their junk when the yard sale is over and don't know what to do with it.
You can go through the items, keep the useful items, give items to friends, trade and barter with other useful items, same some for your own yard sales, and naturally, give what you don't want to your favorite thrift store.
Give it a try and don't get discouraged when people look at you and tell to to buzz off. The next guy may give you a call and be glad to get rid of his "junk".