I've found two search tools, one automated, one partly automated, that help me track subjects of interest in the blogosphere and on the web in general.
Google Alerts notify me via email as soon as Google notices one of my selected keywords or key phrases on the web. You can choose to be notified right away, via email, or have your notices batched and sent all together, once per day. When I get an email alert, I open it and get something like this:
Technorati's Watchlist tool tracks my key words and phrases, too. But Technorati follows blogs, not the web in general. So this function complements Google Alerts.
But it's not as convenient.
I have to log in to Technorati and click on Watchlist, then click on each key word or phrase to see whether anything is new. Often, in fact, there is nothing new, but I won't know that until I check.
correction: Technorati offers an RSS service at no charge, so one can check updates in a news aggregator.
Nevertheless, I'll continue to use both tools to track what's being said about education research, public relations, and related things.