Impulse Responses Library - irlibrary.org

It's quite easy to find some Impulse Response files - they're just spreaded all over the Internet :) What does IR mean ? It's an audio recording used to recreate the acoustic characteristics of a specific environment or filter. Recording a gunshot or a balloon pop provides a good approximation of a space's impulse response. Whether depicting a real space (such as a church with lots of echo), or a specific piece of audio gear (such as a classic tape machine), an impulse response allows one to digitally apply the sound captured by the IR.

There's (at least) one neat place with a lot of Impulse Response files, organized in categories and overall very, very handy - it's irlibrary.org (via Bedroom Producers blog)

Link: IR Library