Thanks Terry 
It's Tom's stuff over at timescapes that's partially inspired me to do this.
I shoot with D200 & D300s bodies, so I have been using the built in intervalometer feature, as well as the Yongnuo MC-36R 2.4Ghz wireless intervalometer when I need funky shutter lengths to get the right exposure or go beyond the 999 frame limit of the feature built into the camera.
I've been shooting timelapse for a while, but am looking to take things up to the next level. My ultimate plan is to have this control a motion control slider too on an Igus rail (I've been reading up on openmoco.org the last few months, but a lot of it's gone right over my head until recently), but taking things easy to start.