You can set up alerts for keywords or specific authors in Google Scholar. Do a simple search of whatever it is you are looking for and you should see an envelope graphic with 'create email alert' alongside it, just before the list of articles and papers is shown.
Or what I do is create alerts for new ToCs of specific journals. This is always a free service. Alternatively you can go into publisher websites and create a number of alerts for different journals. I'm not aware if you can do a keyword alert via different journals though.
I've just checked Sage and it looks like you can do something in addition to a basic ToC alert. Here's what Sage says:
•Citation Alert – from the Article Services Box in an article view, click Alert me when this article is cited
•Correction Alert – from the Article Services Box in an article view, click Alert me if a correction is posted
•Search Alert – click Create a new Search Alert to establish the search criteria for a new alert or click Save as an alert from the Search History page.
Unless there is a meta method I think you will have to go into every database you use and check out their alert procedures.