Much easier to find references to non-electronic articles, book chapters, technical reports, dissertations, etc.
Many resources provide hot links to the citing article so researchers can more easily move from one article to a related article and actually see it in context.
Many databases now offer researchers the option to be notified by email when another article is added to the database which cites a particular article.
Publishers are offering authors more options – including the option of linking their own articles on their personal website and some are beginning to supply authors with usage statistics for numbers of times their articles have been downloaded/viewed compared to other articles in the same journal.
Electronic documents can be tracked by URL – to see who links to a given web page.
University web pages can be tracked to show usage statistics – number of visits to a particular page/document.