Converting SDTS DataThis ArcUser article explains how to locate, download, and process 1:24,000-scale digital elevation model (DEM) data in Spatial Data Transfer Standard (SDTS) format.
Terrain Modeling with ArcView GISThis ArcUser article contains links to resources and articles covering all aspects of terrain modeling using ArcView, and the various data sources that can be used.
Finding Data for 3D Terrain ModelingThis ArcUser article contains a summary of various types and sources for data that can be used to generate 3D Terrain Modeling. Includes a discussion of DLG and DEM data.
Acquiring and Converting DLG DataThis ArcUser article contains a detailed, step-by-step guide to downloading and converting Digital Line Graph Optional (DLG-O) format files for use in 3D models.