Look for a used Nikkor 35-70mm f/2.8 AF. It's a wonderful lens that I'm now using from time to time on my D700 and D3 when I just don't feel like hauling the heavy 24-70 f/2.8 Nikkor. The 35-70 was and is an excellent, sharp and accurate lens. You'll find good ones at $250 and up.
How about a 1990s vintage Nikkor 28-200 f/3.5-5.6 AF? It was never the sharpest lens in the bag, but as an all-purpose lens for the D700 it's a blast. I've got an old one that I dug out of the bottom of my lens storage bag and it works beautifully on my D700. You'll find them used at anywhere from $150-$250 depending on condition.
The Nikkor 24-120mm VR zoom has been knocked badly by a lot of people, sometimes for good reasons. The one I purchased (used) about a year ago is very good however. In any case, there are lots of them around, used, so it's easy enough to find a good one for about $399 if you have access to a few different camera shops that sell used glass. This is by far the ideal zoom range in a walkabout lens for the D700 I think. Plenty of range, lots of wide angle, first generation VR which works really well, and comparatively light weight.
The middle-age Nikkor 28-80mm AF and 28-105mm AF zooms also work well. I just picked up a 28-105 that seems to be very sharp indeed. But like I said above, my 24-120 VR seems to be a particularly good one and I've used it a lot on the D3 and now the D700. Anyway, there are also lots and lots of used Nikkor 28-105mm lenses out there and, again, you shouldn't have any trouble finding a nice, sharp one.
Tamron have a bargain priced DI 28-75mm f/2.8 XR zoom that does a great job for one-third the cost of the Nikkor 24-70 f/2.8. If you're on a budget but still need fast glass, look at this Tammy (if you need some wide angle) and the older Nikkor 35-70mm f/2.8 if you're less concerned about wide angle.
Last but not least, if you find a sharp copy of the 24-120mm VR remember that while it may be technically slower (f/3.5-5.6), the first gen VR gives you two full stops to play with and the D700 adds an additional two stop advantage because of its excellent high ISO/low noise performance.