You can lease the stuff out too!?
Of course, its used as a security (similar to your house etc..).
Watch out for those December contracts!!
P.S here banks dont use gold as a form of security (not sure why) but in Italy its normal to use gold as a form of security to receive a loan (gold is much more liquid than houses so im not sure why its not used here).
Actually come to think of it gold is 1 of the most liquid physical assets there has to be on the market today (selling can usually take place on the day).