The surface of the sun as observed by the Transition Region and Coronal Explorer (TRACE) in high temporal and spatial resolution. Coronal filaments, loops and mass ejections; magnetic arcades, ultraviolet typhoons and X-ray hurricanes; fugitive prominences, earth-bound to create spectacular auroral displays or to wreak havoc on power grids and satellite telecommunication systems — all archived in one giant database.
And by giant I mean you can download 200+ gigabytes of movies in QuickTime and DVD img files!
For free!
Because the surface of the sun is a legitimate site for topographical investigation and landscape design.