Is there any DEM (Digital Elevation Model) or DTM (Digital Terrain Model) for Uruguay or South America?
I am aware of the Renare for Uruguay.
You can download a 90-m resolution DEM from http://srtm.csi.cgiar.org/download. It covers both Uruguay and all of South America.
You may want to check out the relatively new MERIT-DEM, which is mostly SRTM but heavily corrected (especially north of 60 degrees). You can download it in tiles. They also have corresponding hydrologic models (MERIT-Hydro) that include flow directions, flow accumulations, channel widths, height above nearest drainage, and a depression-filled DEM. All global.