A lot of people (like me, say) use anything from MS Paint to The Gimp to Paintshop Pro, as free or cheap - and very flexible - alternatives to 'actual mapping programs'.
Or yeah, the forementioned Photoshop, at the high end.
Whenever I look at what's sold at places like RPGNow, Fractal Mapper seems to have topped some chart or other, or nearly so. Wouldn't know what that's like, but I guess it must have some appeal. . . (?)
My view on Campaign Cartographer concurs with JVisgaitis'.
Dundjinni, from what little I know of it, seems to be very nice for close-in, but not so hot for the big picture.