If you want high-resolution images of the Earth, Unearthed Outdoors has made available the 250m True Marble imageset for a free download with a Creative Commons Attribution 3.0 license. It’s a map of the Earth made up of 32 tiles, where each tile is a 21,000 pixel square, available in png and tif formats. There’s also a series of smaller files that may be more useful — in case you don’t need a map of the Earth that ends up being 84,000 pixels tall and 168,000 pixels across.