One Joomla article feature I'm using a lot at the moment is the Finish Publishing date. It's ideal when displaying specials or competitions that have an end date. You'll find this in Administrator on each article editing page under Parameters (Article). However this feature is not available for modules. Get around this by using a fantastic free extension called MetaMod. In addition to controlling the dates modules appear, it can also:
- display certain modules based on the content of the page
- display different modules based on a visitor's country
- make a module disappear when someone logs in
And much more. Learn more and download here