Here is a list of URL's that offer SFX and also music. Some are free and some for sale.
I have many different "explosion-type" SFX, but do not recall where each came from.
Yes, I've got all my Functional Content "loops," and also many additionals.
I was most curious about the SFX files, available through Adobe from Soundbooth. One can never have too many SFX files in the library. I always find that I need a woman in sneakers, walking in pea gravel away from the camera, and I have a woman in flats, walking on cobblestones toward the camera...