The Sharpen Tool

Now, you may know all about sharpening within Photoshop, with 'Unsharp Mask' for example. But did you know about the 'Sharpen' Tool? In Photoshop CS5 Extended, you can now use the Sharpen tool kind of like how you would use a brush. If you look in your toolbar, where the 'Blur' and the 'Smudge' tools are, you'll see the 'Sharpen' tool. When you click on that, you'll see in your info bar a little icon that says 'Protect Detail'. By default it's already on. Using a pressure sensitive pen, you can apply whatever amount of sharpness to a specific area without bringing in all kinds of horrible artifacts.
So go ahead and play around with it, it could be one of those hidden little gems that saves you an incredible amount of time.
Cheers