sndstretch_xmms is an xmms plugin to adjust pitch and speed separately 
with two sliders.

sndstretch can be compiled as an effect-plugin, with one major drawback 
    - the time and the visual plugins don't synchronize with the song 

and a very basic oss-output-plugin with some limitations: 
    - no additional effect support built in (at least not yet). 
    - the mixer device and pcm device are fix coded as "/dev/mixer" 
      and "/dev/dsp" 
    - the effect is written for normal signed short (S16_LE) and will 
      probably only work if xmms plays such data (...i think mostly it will).