Some of the most impressive effects can be produced by simply using reverb or delay effects with long decay times. These effects may have even more to offer than you originally thought and with a few tweaks and the right technique, really usable secondary effects can be created from them.
In this Quick Tip I'm using Ableton Live, but you can use the DAW of your choice.
Set up a send / return effect in your favorite DAW, using the same technique as you would in any other mix scenario. You can use any sound you like here, so feel free to load up just about any sample. Load a nice healthy reverb (or delay) effect with a good, long decay time. It's the effects tail we are after here, so make sure you can hear one!
With your reverb or delay effect firing on all cylinders you are ready to export. You really need to grab the effect only here and not the sound being sent to it. Some DAWs (such as Logic) allow you to do this by selecting 'no output' on the sounds channel, others (such as Cubase) will also give you options in the export area that allow you to grab just the effects units output.
Now re-import the effect into a fresh track in your DAW and check the result. You should have a pretty spooky sound bed, perfect for editing. Cut off the actual tail at the end of the totally effected sound.
This new sound can be chopped, diced and reversed to create new and interesting sound beds, crashes and reverse effects.
You can even try re-processing the result to get strange and unexpected results. Remember anything you do should fit nicely with your existing project as its original 'DNA' is from one of its parts.
Want to learn even more about sound design? Check out these Ableton Live Tutorials.