I know some of you students, etc. could use a free tank, heck, even I could. Most of the time, you can just tell the salesperson that you're really not interested. They don't want to waste their own time either, and will usually fill out the form. They send the form to your e-mail, so make sure you use a good address...but obviously, your "junk mail" e-mail account and a fake phone number:
http://www.slickdeals.net/?pno=6939&lno=1&afsrc=1