The Nigerian email scam is a spam based scam that is targeting people all over the world. The first thing you need to know about any scam is ANYONE asking for investments over email is not someone to be trusted. EVER.
The name "Nigerien Scam" came from one of the original documents which were mailed rather than emailed with postage markings from Nigeria and other African states. When it hit the email scene the name at the end of the email was often African, thus the name "Nigerien Scam" stuck.
This scam has cost people anywhere from thousands of dollars to hundreds of thousands of dollars.
Should you receive an email about the Nigerian email or 4-1-9 report it to the Better Business Bureau http://www.bbb.org/ and you can also fax a letter to your local representatives office (go on the net and look at the state in which you live dot gov dot org, eg., http://www.ca.gov/ and look up your local representative) informing them that you are a target of such Spam and that you would like legislation enacted prohibiting such offenses.
Even if this email comes from an address that you think you know it is dangerous and should be deleted.