Is there a topic, person or location that you frequently search for when you are writing? Create a Google alert for the search term. When your search term appears on the web, Google will send you an alert to your choice of email or RSS feeder.
Think this isn’t useful to a historical researcher? Think again. Most local newspapers carry columns from historical societies. I entered a regional search term into Google alerts, and I regularly receive emailed links to articles written by local historians. It is true that Google alerts might be more useful if you were, say, trying to keep up with the news on your favorite athlete or monitoring a developing news story. But every historical researcher knows that the best info sometimes comes from unlikely sources. As a historical researcher, cast your nets wide and see what you can haul in!