Re: triggering from the D700 flash - if you're in a darkened room, I think you'll be surprised how wide a field the built in flash can trigger remote flashes - the sensors on the SBxxx units are fairly sensitive.

It all depends on whether you want to remotely control the output of the flash. If all you want to do is trigger, then you could simply go with either inexpensive radio triggers (or the expensive PW's)or optical triggers and use virtually any flash - I've got older flashes that I manually configured and triggered with an optical sensor.

Once you want to start remotely controlling the output, things change and become more expensive in terms of triggering, which flashes you can use, etc. If you haven't already seen his site, go to www.strobist.com - David Hobby is a flash guru and there are a number of posts there regarding how to set things up, trigger, control, modify light, etc. - and he shoots Nikon. Joe McNally also shoots a lot of flash, and is very innovative in his approach, but his budgets are typically larger than David's....