Under the Security options you can automatically enable users to a particular groups upon registration, set time out limits, allow SSO users to see 'Mydetails' link (when hovering over their username on the top) and password security.
You can also remove asset types from the blacklist under 'Extensions to disallow for upload'
Please note: there are several security risks and implications when removing these from the list, including but not limited to malicious people using these file types to stage a front-end phishing attack. To see more info, hover over the '?' next to the section.
