Yes, my SO is constantly going on Facebook and picking up viruses etc so I blocked Facebook from my computer as I never use it and was sick of cleaning all the unwanted spyware and malware she picked up.
See: Facebook Blocker Tool : Free Software to Block or Unblock Facebook on Windows | www.SecurityXploded.com
It worked like a charm. Now she does all her surfing and facebook on her cellphone and not my computer! I am a happy camper!