http://www.dpreview.com/forums/read.asp?forum=1019&message=2363781 Very interesting thread about USM in PhotoShop .

http://www.astropix.com/HTML/J_DIGIT/USM.HTM

http://www.bythom.com/sharpening.htm

http://www.creativepro.com/story/feature/12189-1.html

http://www.creativepro.com/story/feature/11242.html

http://www.bythom.com/sharpening.htm  Interesting article and tutorial

http://www.dpreview.com/forums/read.asp?forum=1010&page=1&message=1553983 Interesting and well worth reading.

http://www.luminous-landscape.com/tutorials/smart_sharp.shtml

http://www.lonestardigital.com/photoshop_quicktips.htm

TIP: sharpening luminosity only in RGB mode

http://www.jtgraphics.net/all_digital.htm

http://www.applied-maths.com/paul/sharpcontrol.zip

http://www.digitalworkflows.com/sharpening/sharpcontrol/workflow.php

http://forums.dpreview.com/... .../read.asp?forum=1006&message=4208293 Sharpening compared on Retouch

http://forums.dpreview.com/... .../read.asp?forum=1006&message=4449395  High Pass sharpening

http://forums.dpreview.com/... .../read.asp?forum=1006&message=4500117  Sharpening out of focus

http://www.adobe.com/products/adobemag/archive/pdfs/9503htdb.pdf  Why Unsharp mask?

Understanding Sharpening - Best Tutorial

High-Pass-Sharpening

creativepro.com - Out of Gamut A Two-Pass Approach to Sharpening in Photoshop

Sharpen The Hair & Eyes

Your best Unsharpen Mask settings Retouching Forum Digital Photography Review

http://www.outbackphoto.com/workflow/wf_17/essay.html  "Mid-Tone Sharpening "

http--www.lindev.org-10D-sharpening Canon EOS-10D-D60-D30 Forum Digital Photography Review and wonderful free action to download

Digital Outback Photo  about Color Washer and Focal Blade

Understanding Sharpening

Movie tutorial by Russel Brown

My web sharpening method Critique please... Retouching Forum Digital Photography Review

Sharpener Review Page About Photo Kit Sharpener

PhotoKit Preview

Contrast Enhancement

Smart Sharp

High-Pass-Sharpening

nic Sharpner

Sharpness

Understanding USM

See also the sharpening tests on this site 

If you have a program that allows you to make individual settings for unsharp masking, try these settings 

as a starting point. They clear up haze amazingly. Amount 30-Radius 60-Threshold 1. 

These settings don't really sharpen, they CLEAR things up.

One may want something easier than USM to achieve sharpening pictures . Here are some :

http://photography-on-the.net/forum/viewtopic.php?TopicID=2412 One of the two very best Linear sharpening actions . by Pekka Saarinen . Free

http://www.2morrow.dk/75ppi/coolpix/actions/  Digital Deluxe Toolbox . Many goodies in one bundle . Free . Enjoy !

http://www.fredmiranda.com/Action_profilesPage/index.html  The other best actions website .by Fred Miranda . Some tools you really can't miss !

http://www.ultrasharpen.com/download.html UltraSharpen 3 is still free.

http://www.applied-maths.com/paul/SharpControl.zip  A small but effective action for sharpening  

Sharpening Actions

Great Sharpening Action by Paul Bleicher

1. Adjustable High Pass Filter
2. Adjustable Edge Mask
3. Darken/Lighten adjustable effects with USM.