Payton White has made available a collection of 75 NXT and technic pieces modeled in Google SketchUp. Here’s an email from Payton:

“I have modeled up 75+ detailed Technic and Mindstorms NXT parts in Google’s SketchUp and made them all available on Google’s 3D Warehouse:
  
http://sketchup.google.com/3dwarehouse/cldetails?mid=26d528c1c35774f056ed665b21152bcd

I believe vetting builds in a tool like SketchUp is quite valuable for the seasoned builder [while at the same time I don’t dispute the value of sitting down with the real parts and snapping things together].  I’ve taken special care to make the parts appropriate for quick snapping and prototyping with the built-in SketchUp functionality.  For my money, it’s a much better fit for Lego assembly than LDraw, etc.
Here’s the blurb I’ve posted for the collection of parts:

Over 75 parts in part groups including Technic pieces and Mindstorms NXT components. Everything is modeled to 1:1 scale within roughly 0.5mm tolerance with respect to the real parts. Snapping helper points are modeled with very high precision. Here are some tips to make using these models easier:

    1) Set Window -> Model Info -> Units -> Enable Length Snapping to
      4mm.
    2) There are two detail layers for many models. Use “HiFi” for the
      most detailed versions and “LoFi” for better interactive use while
      modeling.
    3) There is a “Helpers” layer that includes line segments that
      exactly model where connectors and axles fit with beams and
      bushings, etc. Turn on this layer and x-ray mode for precise
      “snapping” of parts.
Many thanks Payton! Now I need to learn what Google SketchUp is all about…