partconv~ efficiently applies FIR filters with arbitrary impulse responses. Now you can virtually place sound inside a concert hall or even your bathtub in real time, completely within Pd! :)
It requires the FFTW3 library (http://www.fftw.org), includes the source, an x86 Linux binary, and a sample impulse response, and is located here:
http://home.gci.net/~pamsaylor/ben/partconv~-0.1.tar.gz
There is room for improvement, and suggestions are welcome.
Ben