Well just tried this out. Followed instructions above setting D200 built in flash not to fire & Set Group A to TTL mode. D200 built in flash does fire off pre-flash, but then immediately fires off the remote SB800
Using just the menu on D200 I found I could play with the compensation of SB800 no problems. By placing SB800 to side of a subject , I found I could then use the D200 menu to set built in flash to TTL to provide extra light source to image, then play with compensation to get varying degrees of fill in flash vs the shadows produced by SB800 to the side.
Note if you have a SB-600 you need to set the D200 Group to channel 3 (default for SB600). For the SB800 it is channel 1.
Note also you can perform the same from the D80 & I assume the new D300 ?
The Nikon D70/s also has same function, but only 1 group setting & you cannot use the built in flash to provide extra lighting to scene.
So what are waiting for ..... have a play & let me know how you get on