[ryandrake]

One (obscure) example I know of is the RTLSDR-Airband[1] project uses the GPU to do FFT computation on older, less powerful Pis, through the GPU_FFT library[2].

1: https://github.com/rtl-airband/RTLSDR-Airband

2: http://www.aholme.co.uk/GPU_FFT/Main.htm