#1. "RE: D5000 + SB600 question" In response to Reply # 0
Get a Nikon SC-17 (discontinued) or SC-28 TTL extension cord. There is also the SC-29 TTL extension cord priced at about $20,00 - $25.00 more than the SC-28. They will provide full i-TTL flash control just like the Speedlight was in the hotshoe. There are also third party Nikon compatible TTL extension cord available that are a little cheaper but I have never tried one.
If you want wireless i-TTL flash control, you will have to buy an SU-800 ($250.00), SB-800 ($350.00 used), or an SB-900 ($460.00). Good Luck and Enjoy your Nikons!
#3. "RE: D5000 + SB600 question" In response to Reply # 2 Sun 22-Aug-10 03:56 PM by gkaiseril
You would need to buy the SB-800 used, as Nikon has discontinued this Speedlight.
The SB-600 does not have an SU-4 mode remote sensor like the AB-900/800, but if you wanted to set the power level at the SB-600 and have a reliable remote trigger, you could buy a Nikon SU-4 for about $80.00.
If you wanted to use a 3rd party optical trigger, you would need to have a unit with a hot shoe, make sure the hot shoe does not have a large base metal plate that shorts out the off center electrical contacts on the SB-600.