The BBC has a pretty hefty archive these days, which is to be expected after nearly 100 years of operation. Among its archives are sound effects that have been used throughout the decades, and the Beeb just made 16,016 samples available to everyone - absolutely free.
Considering the BBC has been in the TV business since its inception, and radio for even longer than that, there's a lot here. Animals, talking toys, the sounds of nature, gunshots, vehicles, you name it. If you need a specific sound effect for one reason or another, there's likely to be a few options for you to choose from. The interface lets you listen to each one inside the archive, with the option to download it in WAV format. There's a basic search function too, of course, because having to sift through them all manually would be quite stupid.
Obviously is you ant to spend your nights sifting through an absurd number of clips you can. Just make sure to make a note of where you're up to for your own sake, because they're spread over 641 pages.
The downside is that the BBC has made the effects available under a RemArc licence, which means you have to credit the BBC and you can't use the effect for commercial reasons. While some people might throw a tantrum at that last condition, it makes sense that the BBC wouldn't want people to be able to profit from the sound effects it paid for. [BBC via TechRadar]