As mentioned in an earlier post, I've started using Lightroom 2 for my editing. I am really enjoying using it as it is quite powerful yet simple to use. Strangely, the biggest feature for me is something that's available in pretty much every editing program: dodging and burning. Lightroom, all edits are non-destructive including this one. Since you are also dealing with the RAW file you also have a lot more data available making it easy to pull out the detail in the shadows and highlights. As an example I took this picture of an old house and worked the image a fair bit and converted it to black and white. I burned the sky and dodged the house itself.
South of Cochrane, Alberta. Nikon D50. Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED lens at 18 mm. ISO 200, f/8, 1/50 second.