Many sites have community blogs and twitter accounts that automatically pull well-received questions and tweets about them online. Here is an example:
An Aviation Twitter Thing
Generally, what they tweet is the question, a link, and a hashtag with the main tag assigned to the question.
These are basic items: they are generally pulled off by Stack Exchange.
What's interesting is the unique ways that sites promote themselves. You're first bet is to promote across the existing SE community. There are neat things called Community Ads. Graduated sites will have a post with the community-ads tag. This is a special tag: Any "answer" (an answer is an advertisement) that is voted up with a score of 6 or more will automatically be displayed in the sidebar of the site. Here's an example:
That's a simple community ad that I've made to advertise an Area 51 proposal on other sites. Posted on GIS Meta, it's a neat way to share the word on sites that are related or with communities that hold an interest in this kind of stuff.
This is the time for a community to be creative: finding great ways to show off a community to the world. Find organizations, find other communities, use groups: If there is a tool available, use it!
This post has been migrated from the Open Science private beta at StackExchange (A51.SE)