Space is big, and as such, things that'd hit a spacecraft hard enough to do damage are few and far between. I'm not aware of a single spacecraft in history being disabled by naturally occurring debris.
I believe Cassini also flew through a gap in the outer rings during its initial positioning, using the communications dish as a shield against residual dust. There was also a recording released that transposed the energy dispersed from the impacts into audible noise. I'll see if I can find it.
Edit: Here we go. Info [1] and sound [2]
[1] http://www.esa.int/Our_Activities/Space_Science/Cassini-Huyg...
[2] http://www.youtube.com/watch?v=9rrc5pxRdLc