Snopes.com says both the North American Union and the amero rumors are false.
Here's what Snopes.com has to say:
http://www.snopes.com/politics/immigration/nau.asp

About the amero:
http://www.snopes.com/politics/business/amero.asp
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"I didn't care what she didn't 'low--I would boogie-woogie anyhow" John Lee Hooker