When people think of scent glands they usually think of an animals rear end. You know, anal glands? Skunks spray them and other animals rub them on vertical surfaces. But sugar gliders have three scent glands, one of which is very obvious if you have one of these male marsupials.
Male sugar gliders have a scent gland on the top of their head. It looks like a little bald spot and he uses it to claim his mate and offspring. Don't worry, it's not male pattern baldness.
For more information on sugar glider scent glands, including the location of the female scent glands check out this article.