For those passionate about 3-d and Digital Terrain Modelling, MadMappers have void-filled data from the Shuttle Radar Topography Mission (SRTM) and produced a 2 DVDs collection of 90m DEMs which are fully compatible for use in OziExplorer and other GIS software. Cost is Rand 100 per DVD (US$ 17) plus postage. Read more on the Shuttle Radar Topography Mission on the SRTM page.