The Gravity Builder was developed to enable the easy
construction, in Opensim immersive worlds, of staircases,
ramps etc. which need to follow a slope. As the ball rolls
down a track (or a hillside) it rezzes prim's or linksets
along the way. It includes a number of options, including
complex smoothing, step separation and many others. It
is free to use or modify and you can get a copy at the
OSGRID, Wright Plaza Freebie Mall. Or, for use on your
own grids, as an IAR file here