STEP or IGES for components is a natural development direction, as I also feel. I am actually seeking for a alliance with a 3D component models repository. I am targetting automatic models download. Also, The STEP/IGES export of a complete mounted board would make sense.
ZofzPCB.com - There is a free 3D PCB preview tool, a 3D Gerber Viewer. It is reading a set of CAD2CAM files usually automatically. If IPC356 "netlist" file is included, you can browse by components, pins, nets (and compare the copper to the netlist).
The software uses Direct3D - that is it is converting the painting into optimized triangulated surfaces. Benefit: speed of rendering. Disadventage: up to some size, depending on the GPU. The rendered image is quite different than symbolic 2D representation, this lets you spot another errors, then a 2D adapted eye.
I was trying to add some pleasure to the task of PCB checking: guessed components visualization (no BOM and lib yet), autopilot, transition effects.
Although an old thread, someone earlier mentioned PCB123 as an option that fits in all of the categories. I've done some home projects that used their software and think it is certainly a great addition to this list.
I would like to add that creating a footprint is especially easy, less than 5 minutes from scratch for a part that has 1-20 pins. You can do multi layer boards (more than 2), the turnaround from the manufacturer is quick and if you don't need cutouts or anything really special for a two layer board it may only cost $50 (1-2 small boards) to turn something out with shipping.
That doesn't make sense for us; our machines are pretty small, and I'm working on replacing discrete wires (typically running in wire duct) with standard or easy to make cables connecting to custom PCBs.