I'm pretty sure I mentioned before that my all time favorite resource for homeschooling is the library. Our library is phenomenal! I'm pretty sure I could give up teaching art, literature, science and history and instead just sign my kids up for every class the library offers. But to say it's my favorite free resource is a little disingenuous. Because I have two.
The other favorite free resource of mine is a website - The Well Trained Mind. The forums on this site are bang on fantastic. If you have a question about anything from grammar to teaching styles to how to cook cabbage these folks will be able to answer it for you. It's the most active board I've seen for homeschooling and the folks are great. It's like a big family. I could go on and on, but you've got to check it out. In fact, it's the only resource I'm going to post today because I know once you go you'll be hooked!