I find the background image of the Travel.SE and Travel.Meta.SE websites (world map with hexagonal tiles) very appealing.
Are they available for download to use privately as desktop background etc.?
The map, along with the logo and other aspects of the site design, is copyrighted by Stack Exchange, Inc., which so far as I know does not license the creatives to anyone.
For private personal use, however, there is nothing to stop you from simply downloading it from https://cdn.sstatic.net/Sites/travelmeta/img/bg-map.png (or copying this file from your browser cache).