Most search engines, Google included, require you to enter a search term in order to retrieve content that already exists on the Web. But what about new information that is published after your search? For that, you can turn to PubSub. Enter a term and PubSub will send alerts to you via RSS when new content appears. Frank Barnako of CBS Marketwatch has the story, along with an interview with PubSub founder Salim Ismail. So far, there are no news feeds, but Ismail expects that could change with an agreement with a news syndication service. PubSub does search blogs, SEC filings, press releases, airport delays, and newsgroup posts.