I'd like to chime in, albiet a bit late. Sharpening is not a one-size-fits-all thing. In an ideal world, you would sharpen each image individually for optimal results. This isn't an ideal world and most people who process volumes of images want some compromise setting that gives a good effect most of the time.

Rule of thumb 1: Never sharpen at other than the final intended size.

Rule of thumb 2: Do not save in a lossy format such as JPEG, reopen the file, and then sharpen. Simply create a merged layer on top of all the other layers and sharpen that, then save for Web.

Rule of thumb 3: Before sharpening, convert to the output color space, sRGB. This is a weaker rule than 1 or 2, but you're going to need to do this anyway, so its better to perform the operation with the destination gamut in play.

Rule of thumb 4: Save your unsharpened original so if you need to resize, repurpose, or revisit the sharpening, you have the source image with edits but no sharpening halos.

To better understand what's going on here, it's useful to understand how sharpening actually works. What happens in almost all sharpening algorithms is that edges that contrast in luminance more than some threshold amount are identified as "edges." These edges are made to look sharper by increasing the luminance of some number of pixels on the bright side of the edge and decreasing the luminance on the dark side.

Over the years, there has been much debate about color artifacts introduced by sharpening, hence the high-pass method or sharpening the L channel in the LAB color mode. At this point, the amount of research Adobe (in particular) has done makes them well qualified to cook up sharpening algorithms that will effectively sharpen without undesirable artifacts.

All Photoshop sharpening algorithms work just fine for Web output provided you have 1) a composite layer (as I described previously); and 2) you have resized the image to its desired output size. You may have better results with less intervention required on your part by using Sharpen or Smart Sharpen. It depends how much you trust the smarts of these filters -- trying them on a representative sample of images will tell you which you like best. For ultimate control, Unsharp Mask is still the tool to use. You pull all the strings with Unsharp Mask and don't rely on smart-anything to make decisions for you.

Finally, many professionals swear by NIK Sharpener Pro. You can download a demo from their site and take it out for a spin. If you like their results better, you can evaluate whether their results are better than Adobe's.