Spent some time looking at candidates for the map and came across some interesting projects (I'll flesh this out tomorrow):
Open Layers - specifically this example. The gallery has some good links, too.
The sundial example covers much of what we need code-wise, but we still need a good base layer for terrain. I think we should focus on Blue Marble data. It's free (not sure about open-source) and has many example apps that compete with Google Earth, many in Java.
The data we're looking for is frequently referred to as the 64K BMNG image (alternatively, the 84K BMNG image); it's huge, though, and in an odd format.
A standalone app that I'm looking at to assess data (and maybe figure out where to get it) is EOLi. The app itself isn't necessarily of interest, but the data it grabs might be useful.
More excellent resources:
* USGS seamless server. It appears to offer very high res images for download (max of 1.5GB/?).
* USGS Global Visualization Viewer (aka GloVis)
* NASA FTP site with most (all?) of the SRTM data in obscure (context-specific) formats like hgt. (Here's another, and another FTP site). I have no idea how to convert these, but ...
* and this is a listing of tiffs from the NASA Photojournal.
* another download helper app.
* and another one.
* a tutorial for handling some of the data. And another one.

A Google Earth competitor is WorldWind, and it uses Blue Marble data as far as I can tell. Cache packs of data are available here.
I've emailed for further info on some SRTM data that is advertised here.

So far, I can only find Windows apps to read alot of these files:
3DEM.
MICRODEM.
Global Mapper.
I'll try them out tomorrow.