If you're one of that rare breed that actually sits down in the same room as friends to play SR or any other RPG, and you tend to have a computer in the same room, and you like to toy with new ways to spice up your games, Soundplant, which is freeware (but nothing to do with me), might be worth playing with.
It basically turns your PC and keyboard into an audio sampler, so by hitting a key you can start a loop of atmospheric background noise, and/or trigger one-off sound effects (like screams, gunshots, animal noises, thunder rolls, metal creaks or whatever). It can play a fairly large number of samples simultaneously (depending on the specs of your hardware), and it's relatively simple to assign samples (wav or mp3) to keys. Plus you can save 'keymaps' for future use.
You can quite often borrow suitable sound effect clips from computer games (if you can find them- some newer games tend to bundle them up in special archive files and then you need to download special software to unlock them, but it's doable). I won't name games but you can probably figure out some good ones to try.
I've used this to good effect in the occasional special session and it can be quite a cool way to set the mood. So I thought I'd pass it on, on the offchance that somebody else might find it useful.