Tell blog search engines and news aggregators every time a post is added to a blog so that they can index the new content. Telling blog search engines you have updated content is called "pinging" them.

According to the definition on Feedster, "A ping server is a bit of software infrastructure, a server program to be specific, which lets a feed tell us 'I’ve just updated; please index me now.' What it receives is a small tidbit of information from a blogging or publishing tool which is called a 'ping.' Hence the name."