I wanted to make something with eight legs. Why not? There's no law against it.
The legs were modelled in Ray Dream Studio, between crashes. Each leg is actually a fully linked and articulated model to make posing easy. Linking objects in RDS is a lot of work, but worth it.
The hull - which is significantly simpler - was made out of two Ray Dream freeform objects, to which eight copies of the leg were attached. The legs were then posed individually, tweaking the joint angles to move the various parts of each leg in different directions. The model was then imported into Bryce in 3DMF format.
A modified standard texture was applied for the mechanical look. Heavy bump, the secret solution to under-complex models (the hull is really very simple), helped create the illusion of detail.
The figures beneath the vehicle help to give an idea of scale. They were modelled and rendered in Poser, and then imported as PICT objects.
If you don't know who Sleipnir was, you can look it up. The Wikipedia entry even explains why Sleipnir had eight legs.