Acrobat "Paid" stamp

The blog author says:
"I have no plans on writing a tutorial...After wasting over an hour looking though worthless tutorials on how to write javascript for Acrobat Forms, I came up with paidstamp1.pdf. Feel free to use it for yourself."
http://www.naterkane.com/blog/a-dynamic-paid-stamp-for-acrobat/

And if you want to know how to do it, here's an actual tutorial:
http://blogs.adobe.com/acrolaw/2006/08/creating_custom.html