I've been using the High Pass Filter (HPF) method for content sharpening for a while now and am fairly happy with it. I just wanted to share the method and see if anyone else uses it and what others think of it.
For those not familiar with this method, here is a brief summary (based on CS5).
Once all destructive editing has been done on the main layer (eg cloning, Shadows/Highlights, brushing etc), create a duplicate layer (which I call HPF). Then with this layer selected, select Filter/Other/High Pass. Then a dialogue box will come up for selection of the pixel radius. I usually use about 4 for a full res image (18MP) from my 600D but for smaller size images this should be changed (eg probably about 2 for a 12MP image).
When making this selection, you can get a good idea of those parts of the image that will be most affected by the final sharpening.
Then with this layer selected, select a suitable blending mode ( I use Linear light but others such as Soft or Hard light can also be used) and set the Opacity to a value that gives the desired amount of sharpening ( I usually use about 30%). Varying the Opacity varies the amount of sharpening.
The reason I like this method is that it is non-destructive - it can be turned on and off at will after saving the PSD and the amount can be changed at will. (eg if you've gone a bit overboard with the sharpening and want to peg it back). Setting up an Action for this procedure makes it very simple to apply.
You can also put a mask on the HPF layer to do selective sharpening in certain areas of an image only
Dave