From time to time, Judaism.SE community events, such as the Ingathering Contest, the weekly topic challenge, and Parashat Hashavu'a Chat are discussed or announced here on Meta. In the past, we've used a banner at the top of the main site to advertise these events, but we have learned that SE policy is that such banners are only to be used for very rare situations, so we will no longer we using them.
If you would like to know when such events are announced, please try one or more of the following:
Come visit Meta from time to time. You'll see announcements as well as all kinds of interesting discussions about site policy and other community matters.
If you see a "Visit Meta" section in the sidebar of a question, take a look. The most relevant announcements are usually linked there.
If you just want to see current announcements, bookmark at Meta's featured tag.
If you use a blog-reader or other RSS tool, subscribe to the
featuredRSS feed, and you'll always be notified of new announcements.
Check out our scheduled chat events, and register for those you're interested in. (Right now, there's only one, really.) You'll get automatic notification when it's coming. You can also export a calendar item for your Outlook/Google/whatever calendar.