Insert today's date in Mac OS X. Add as a Service via Automator using AppleScript, to create a Shortcut.

TODAY service

on run
	# TODAY - Returns today's date!
	# Create your own Service, to avoid 3rd Party software (WordService, etc.)
	# In Automator:
	# > Service receives 'no input' in 'any application'
	# > Output replaces selected text
	# Add Shortcut (e.g. Ctrl+Cmd+T - it's hard to find a free shortcut!):
	# > Preferences > Keyboard > Keyboard Shortcuts > Services
	# When setting up Keyboard Shortcut, *exit* the target app before testing. (It seems shortcuts are only refreshed when app is launched)
	# Adjust 'Short' Date format
	# > Preferences > Language & Text > Region.
	return short date string of (get current date)
end run

# Sources:
# http://apple.stackexchange.com/questions/100642/how-to-make-an-existing-applescript-file-to-work-as-a-service
# http://henrysmac.org/blog/2014/1/4/formatting-short-dates-in-applescript.html

Thanks for this :)