RSS Feeds or e-mail alert services may help you by keeping you up-to-date on a topic of your interest.
Many journals offer RSS feeds directly from their website. Alternatively, you may register simultaneously to several TOCs (table of contents) through JournalTOCs services.
Services such as ChangeDetection.com notify you about changes in websites that you have selected.
Alerts search engines such as Google Alerts notify you about websites relevant to your topic of interest you may not be aware of.