I just want to add a quick addendum to the code above as it wasn’t working for 2015 and there is no information really anywhere on how to extract these well.
from pymel.core import *
for item in resourceManager(nameFilter='*'):
try:
#Make sure the folder exists before attempting.
resourceManager(saveAs=(item, "C:/temp/icons/{0}".format(item)))
except:
#For the cases in which some files do not work for windows, name formatting wise. I'm looking at you 'http:'!
print item
Before, without the nameFilter argument, calling to the resource manager with no argument would return none.