For cyberstalking, there is an excellent group that can provide you with tips and advice:
www.cyberangels.com
This site has advice (it's from the UK, but still applies)
http://www.thesite.org/youthnet/jsp/...p?d=171&a=2085
Keep copies and a record (as well as a diary with dates and times) of EVERYTHING! Don't respond with fear as that's what the individual is hoping to get from you. Tell them simply to stop.
Stalking IS a crime. Insist on fiing a police report so you can start a paper trail. If the local police won't help you, go to your county sheriff or state police. You can also go to the FBI if there are threats.
You might want to consider taking a martial arts course. It's very empowering.