For who ever likes to use DEMs and GEOTIFF.
Build Accurate Terrain Databases Quickly and Easily with Scenome.
http://www.scenomics.com/index.stm
I would like to add http://seamless.usgs.gov/Website/Seamless/viewer.php?startbottom=-85.0&starttop=85.0&startleft=-179.5&startright=179.5&limitbottom=-85.0&limittop=85.0&limitleft=-179.5&limitright=179.5
Nothing ever runs on Macs :(.
Here's a link to the USGS 1-degree DEM data for Scenome.
http://edcftp.cr.usgs.gov/pub/data/DEM/250/