One of the toughest aspects of landscape photography is <A HREF="http://www.popphoto.com/popularphotographyfeatures/5168/how-to-fix-the-sky.html">getting a rich, deep sky</A> without underexposing the ground. Sure, there are camera-based solutions such as optical filters, but sometimes these aren't practical. It's easy enough to add drama to the sky in Adobe Photoshop--the hardest part can be doing it realistically and avoiding the telltale white halo.
Here's an easy way to double the density and power of your whole sky, with a concurrent trick to disguise your work. You'll need Photoshop for this one (sorry, Elements users), but any fairly recent version will do.