Seems like some people really like B&W portraits, and some people don't... I do. I like the simplicity of B&W images. Generally I think the best portraits are simple, without a lot of busy, distracting elements. Removing the color from an image helps to simplify the photo and really concentrate the viewer's focus on the subject.
Actually "black & white" is not very accurate- I prefer images that have a subtle warm color tone. This "duo-tone" look is more pleasing for portraits. True black and white portraits can make the subject look very cold and lifeless- typically not the look we're going for. Nonetheless, I will continue to use the term black & white, even though we all can agree that black & white doesn't really mean black & white :)
Some images seem to make better B&W's than others. Usually I find that simple, close-up shots work the best. But I don't really know how good an image will look in B&W until I try it. When converting to B&W, there are two key elements that I always add. First is the warm color tone we already talked about, and Second is Contrast. B&W images look great with a lot of contrast. (Lightroom users- also try adding some Clarity)
You don't need special software to create B&W's, but if you want to get serious about it, there are some great applications out there designed just for B&W conversion. The most popular is Nik Software's - Silver Effects Pro 2. It's pretty awesome and it is free to try for 15 days.
I always recommend Google's Picasa photo editing software for novice photographers. I used Picasa exclusively for a long time. It's very very capable, and it's very very FREE! Because it has become a very popular editing platform, I wanted to put together a short tutorial on converting B&W images in Picasa. So, even though I'm one of those people who HATES hearing the sound of my own voice- I thought a screen video would be best to explain the procedure. --
B&W Conversion in Picasa from tim wyler on Vimeo.