I'm looking for open-source or publicly-available terrain data, for instance heightmaps or DEMs -- ideally GeoTIFFS by way of an easy-to-use API. For instance: you pass a pair of lat/longs and maybe a resolution, and are returned an image, possibly wrapped in some XML.
The sources I've found so far require complicated dances through maddening interfaces to acquire data, which further requires lots of manual labor to be made useful. Does my dream source exist?
[Edit: YES IT DOES, I helped make it. See my answer below]