Anyone have a good source of sound effects?

In the prep work for my stint as a Keeper of Arcane Lore for Call of Cthulhu, I browsed around for some sound effects to use as ambient background noise during the session. When we played Beyond the Mountains of Madness, our Keeper had managed to find some very good noises both for the boat trip to Antarctica and for when we was on the ice. It managed to give that extra subtle but constant reminder that we "were" in another place.

What I did find now when I searched, was only short snippets that either faded out or faded in. If you wanted to have them as ambient sounds in the background, you'd get some very annoying clicks and points when the sounds would go away before suddenly re-emerge. Needless to say, looping them just didn't work.

So, where do you go to find good, loop able, sounds for sounds of weather and general noises in rural or urban areas? Anyone have a good stack? Do you know a site where they reside? My google-fu wasn't up to it before the session, and I thought I should try other methods before the next one.