Some other icon sets (probably appeared on HN before, don't know where I got them from):
flags: https://www.gosquared.com/resources/flag-icons
user interface: https://www.gosquared.com/resources/165-vector-icons and http://adamwhitcroft.com/batch/
flags: https://www.gosquared.com/resources/flag-icons
user interface: https://www.gosquared.com/resources/165-vector-icons and http://adamwhitcroft.com/batch/