Linux: write a network image to an SD card
If you have a fast network connection you can read an ISO directly from the Internet and write to a flash drive, or SD card. Just pipe curl to dd (requires root) and you're done.
curl ftp://mirror.web-ster.com/centos/7.2.1511/isos/x86_64/CentOS-7-x86_64-NetInstall-1511.iso | sudo dd of=/dev/sde