Several years ago, I spent the majority of 8 hours googling free sounds fx. The ones I saved were filed away, but that's before I recorded if they were totally free or if they had some restrictions.

There were several really good free sound FX sites on the net however. I will try to find thm again, but if not, spend some time googling for Sound FX, Free only, then check out the terms.

The majority of sites have you pay a fee for use, like Sounddogs.

Also, depending on what your looking for. You can get voice recordings and the like from Libraryof Congress. Being a military guy, I found quite a few military type sounds, like aircraft, service related and the like.