The ultimate general purpose lens is the 18-200mm VR. It covers a wide range, from wide angle, to telephoto. The VR or vibration reduction is very effective, too.

For portrait work, he'll need something with a wide aperture; something like f1.8 or wider. The obvious choice for people not wanting to spend a lot of money is the great 50mm f1.8. On a 1.5x cropped body-such as the Nikon D80-the 50mm is more like a 75mm lens; a near perfect focal length for portraits.

Of course, you can go with a number of other choices, like the 50mm f1.8 and the kit 18-70mm. Or a 24-70mm f2.8. Or even a 17-55mm f2.8 and a 70-200mm VR. The possibilities are based upon how big of budget you have.
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If this is his first digital SLR, you might not want to buy the 18-200 VR lens that costs almost as much as the D80 does. It IS a great multi-purpose lens and the "VR" feature is a great help, but if you want to take it easy on the budget for starting out, there are a couple of other combinations worth considering.

D80 + 18-55 VR – $949.95
D80 + 18-135 – $999.95

The 18-55 is the most common lens included in an intro kit because it has the most universal appllication. The 55 mm end is useful for portraits, although (as mentioned) a 50mm f/1.8 prime lens is a good choice fro portraits. The 18-55 "VR" is a pretty nice lens and the "VR" is a valuable aid to getting sharper pictures.

The 18-135 lens will probably be more fun, because it zooms out a bit more for getting "up close" to the subject. This particular lens lacks "VR," but that's not the end of the world, either.

Dollar-for-dollar, for a beginner, I think I'd get the D80 with the 18-135 lens and let him decide if he wants to turn around and spend another $700 for an additional lens once he sees what his interest level is.

If you want to get an idea about the different focal lengths (in case you are new to this, also), see http://www.flickr.com/photos/samfeinstein/476181737/

The first 4 frames would be available from the 18-55 lens. The 18-135 would give you the first six and the 18-200 would give you the first seven. Of course, an SLR zoom would give you every single focal length in between those shown in my example, too.
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I vote for the D80 with its common kit lens, the 18-135. After some experience, he will know better what he's missing from the lens lineup. The 50mm f/1.8 is hard to beat, and a great portrait lens on the crop frame sensor. Also get him a SB-600 or SB-800 flash, which will probably have more immediate use than an extra lens.
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