Also check out soundeffectsplus, soundgator, and soundjay, who's libraries all overlap because they are owned by the same company, and I don't know why they did it that way but what ever, it's allot of good stuff.
Then their is zapsplat and freesfx.co.uk.
For some of the ones with more advanced licenses, it basically tends to boil down to, as long as you don't directly share the sound files to another person or make downloads available for the sound files them selves, or use them in a program specifically about sound effects than your fine.
Just remember to attribute appropriately, the FAQ or license will explain it, and you can also email most of them if your not sure.
Also check out Airborn sound, I forget if that's on the list yet...
Open game art.org, sound bible, and freesound all have very good stuff if your willing to look for it and do some cleanup, and in some categories, like ambience for freesound and 8 bit effects for open game art, the selection is really good without even looking, and both opengameart and freesound offer packs, so that helps allot.
The 4 Sonniss GDC bundles are also a really good resource, though you'll need enough space to store them and 2015 is harder to get.
Also their is the Adobe Audition sound library which, surprisingly you are allowed to use outside of Audition and doesn't even have a super restrictive license.
i'm pretty sure that all of these are good in commercial productions too... Though then proper attribution is even more important.
This... -- Is CNN'.
Well Ted, it sure looks like there's been uh, quite a bit of violence around here
"aaoh, that violence was terrible'!"
Yeah it was, pretty bad.