Are you feeding the signal in live or just post processing it? I find that as long as you don't get crazy with the number of effects, software DSP is an awesome pastime and you can produce some amazing results on par with the hardware synths. I just recently got into using Fourier transforms to work on sounds in the frequency domain and it's amazing at what can be done in real time.
I'm just post processing, but there is no reason why it can't be done in realtime as well. I'm just to lazy to write a streaming audio in/out framework with low latency.
The effect is btw fft-based. It's just a pitch-shift, +7 cents on the left channel, -11 cents on the right mixed with 50% of the original signal. FFT-blocksize is 512 samples, overlap-factor is four. I started with much higher numbers (2048 blocksize and overlap of 32) but it turned out that I wasn't able to hear all the extra quality.
BTW, that beagleboard is crazy! Still prefer my netbook, but that's some snazzy tech.
The beagleboard is a fun toy, and a lot faster than you might think. The Cortex-A8 CPU does a good job and has the best designed SIMD-unit I've ever seen. The real fun starts if you get the DSP going.
I do all my coding on a notebook though. It's much more comfortable. When I'm done I'll port the stuff over to the beagle.