Paul Doornbusch wrote:
>
> The best way to record them is probably with something like
> a portable dat, great microphones and a stack of balloons and
> pins to create the impulse.
> 
> Paul

I agree with Paul, but would add a balloon inflator to the equipment list.
According to Russ Berger, an acoustics designer I trust, if you blow up a
balloon until it pops, instead of popping it with a pin, you get about 10 dB
more acoustic output. Looked at from the other direction, this would lower
your noise floor by 10 dB. 

If you use a balloon inflator, you can be some distance from the balloon
when it goes off. Get as far away as physically possible, because you don't
want the balloon blowing up in your face or next to your ear. At the very
least you would get temporary threshold shift, so you wouldn't be able to
hear that last beautiful bit of reverb tail your trying so hard to get.
Other, even more unpleasant surprises may await you.

Also, if possible, try recording several files with different mic and/or
source placements in the room. This will not only give a more complete
picture of the space, but could be rewarding to use in multichannel playback
or interpolating between them for "movement" effects.

Happy popping.

-David.