Bernhard Lehner my geography colleague from Burnside Hall at McGill has recently released HydroSHEDS a new global map of the worlds rivers. Maps based upon this data were featured in the March issue of National Geographic.
a new hydrographic mapping product that provides river and watershed information for regional and global-scale applications in a consistent format. It offers a suite of geo-referenced data sets (vector and raster) at various scales, including river networks, watershed boundaries, drainage directions, and flow accumulations. HydroSHEDS is based on high-resolution elevation data obtained during a Space Shuttle flight for NASA’s Shuttle Radar Topography Mission (SRTM).
It can be downloaded from USGS at HydroSHEDS Data.