Found this on Ozbargain. I figured a free pen and Lanyard would be good of geocachers even if just for swag. Best you use a junk email if you are going to sign up. A junk name and dob would not hurt either.
There is no email validation on sign up so you could even use a non existing email I guess.
"The pack includes 28 Page Terra Infopaper,Quality CANNA® Pen,CANNA Ape Lanyard and 2x CANNA Stickers."
http://www.ozbargain.com.au/node/27265