I do it occasionally, but only to the point that the body (of the D80) would have allowed. I have my D80 always set to normal sharpening and apply any additional sharpening as postprocessing (with CaptureNX).
Usecases are: slight shake, slight out-of-focus, or to give a finely grained structure more oomph/contrast.
If you have more than slight shake or out-of-focus, you're out of luck. Also be careful if you have some grain due to high-ISO/low-light: Sharpening will make the pic even more grainy.
See a 100% crop
(409x578 pix)of one of those finely structured pics from NZ at 0 sharpening (left) and at full sharpening (right).
On the D80 normal sharpening factory default is "3" at a scale from 0..5. If you use the unsharpen mask of CaptureNX or Photoshop you can get more pronounced results.
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
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