There's [rojo~] in mrpeach, if by brown noise you mean red noise. (brownian noise?)
[rojo~] tends to grow out of bounds, which is a problem with correlated noise: if you want long term correlations you have to be ready for the noise to get very loud. So in practice there is no red noise possible, it's all high pass filtered.
To get any arbitrary shape of noise it can be done most efficiently by convolving a frequency curve table with white noise. The table would have the same length as the number of bins in the FFT.
Martin