I made Earth, and I've uploaded the 2 gigapixel diffuse texture for you wonderful internet people.
For a recent project, a client required a high res earth model... quickly. I set about sourcing everything needed to make it happen, starting with the best textures i could find. The diffuse here is sourced from a 4 gigapixel image i put together from 6 NASA blue marble tiles (86,000x42,000 or thereabouts) , with 42,000px cloud textures, city lights and spec map. Just how sharp is this thing? Here's Cyprus
I recommend 16GB of ram or more for use of this one. Have fun and happy rendering!