Publisher websites are where articles are first provided, prior to their being sent to database vendors. Publishers often provide information on research articles while they are still "in press" unlike databases which do not often include content until after it is officially published, sometimes for weeks or months after it has been made available on the publisher website.
Publishers also offer the option to sign up for alerts regarding articles in all of their publications and journals without the requirement of a subscription to the journal. The drawback to publisher alerts is that they usually cover a fairly small number of journals while database alerts can cover several thousand journals.
Scholarly journals publish a "feed" containing the Table of Contents (TOC) for their most recent issues. The TOC updates will come up as alerts in the feed each time a new issue is published. This provide a convenient means of staying informed about developments in an academic field.
Both email and RSS feeds are available among these Publishers. Some include the option to join them on Facebook or follow them on Twitter,