I like the FM plug-ins and photokit (pk) sharpener works great as well but the smart sharpener built into CS2 is all you need if you take the time to learn it.
CSPro is great because it uses masks and some other intelligent actions and gives pretty good results without needing too much knowledge. If you're shooting jpegs the camera really does most of the sharpening (unless you're using the faithful picture style). I've never been a big fan of in camera sharpening, best to shoot RAW and use smart sharpen, CSPro or one of the other good edge sharpeners out there after you process the RAW image.
The general sharpener and edge sharpener built into Aperture's RAW processor are unbelievably dialed in, the RAW photo just pops off the page with std settings.