Bravo! That's the most thorough overview of Photoshop sharpening techniques I've seen.
There's a handful of new plug-ins as well that do a good job of sharpening, which can sometimes be more cost-effective than spending the time to learn sharpening theory. I'm partial to PixelGenius'
PhotoKit Sharpener, but
FocalBlade is also good, albeit only for Windows.
Asiva Sharpen+Soften is a Mac/Win product for the ultra-technical sharpening wizards: it's the only one to permit using curves to define how the sharpening will affect colors, light- or dark- colors, etc.
One other variant of USM is to create a copy of the image in a new layer (merging to a new layer, duplicating and flattening, whatever), then sharpening the copy as normal, if a little stronger than typical, using any non-brightness-oriented sharpening. Then adjust the advanced blending modes ("gray" channel) to reduce the effects in the deep shadows and extreme highlights. One place to start is to move the black and white point triangles to about 15 and 240, then splitting each and bringing them 10-30 points towards the center.
It gives a simple, if not as flexible highlight/shadow "mask" effect, without the need to do the masking itself.