Public relations has always been a powerful marketing tool and the Web directly enhances its power.

The extra importance of PR on the web is due to the web being its own media environment.  Press releases can be distributed at minimal cost to sites where journalists and relevant experts are likely actively to be seeking such information.  In addition for every site that indexes the release there will automatically be a link back to your own site with beneficial consequences for your link popularity rating and hence search engine rankings.

If you already have an offline PR campaign running, there is likely to be no extra cost involved.  The main change will be during the authoring of the Press release to ensure that keywords are used and presented to best effect as on any other standard web page.

Apart from specialist PR services, significant results can be achieved in improving search engine rankings simply by regular site updates. If you are adding a page a day for a new product or service, the search engines will quickly learn that they have to spider you daily to keep up to date.

You should also consider adding an RSS news feed to your site.  This is a way of presenting the same news content as you might have in a newsletter or new product page in a format designed for easy digital communication.  At present it is still early days for effective use of RSS feeds and Blogs for practical marketing; but they have the potential to replace email newsletters as the standard way of keeping your prospects up to date.