locating midpoints of polygons?

[Jacinda M. Barbehenn]

Does anyone know of any program (in GRASS or whatever) that will determine
the midpoint of a polygon?  It should be able to generate a point that's
always INSIDE the polygon.  

OR -- At one time I think there was a GRASS program that would figure out 
the largest circle that would fit inside a polygon.  The center of that 
circle will be a good midpoint, but what was that program's name??

-jacinda barbehenn
 USACERL/UI GISLAB
 mountz at gis.uiuc.edu