A360 VIEWER - Free online CAD Viewer
STP Viewer - Free STP Viewer - free software that lets you view 3D STEP files (.stp, .step file format).
Glovius - Extensible & customizable 3D viewer, for consumption of product design data.
IGES2STEP - Freeware CAD file viewer for Windows XP/2000/NT
PartXplore - The most powerful, high-speed?CAD file viewer and analyzer
IDA-STEP v4 - Iges2step is a free and elegant CAD viewer application for Windows.