There are also userscripts like sidewiki that can be installed in web browsers that support userscripts to display the comments that other users have left.

The page owner, or webmaster, could like anyone else leave comments about the page but they were not handled differently from all the other comments meaning that it could very well be that the webmaster comment slipped down so that it could not be seen on the first page.

Google made up their mind and decided to provide webmasters with access to a special section in Google Sidewiki called page owner entries. Webmasters who have added their websites to the Google Webmaster Tools can now add page owner entries that appear above every other comment that is being left on their website.

The service to add page owner entries to Sidewiki is located in the Labs section of the Google Webmaster Tools site. Webmasters can write text and spice it up with a few HTML tags that are allowed like breaks, text formatting and even links. Webmasters can also use a generic text instead if they prefer that. It takes a while before the entry is shown in the Sidewiki comments but it can be used to inform visitors about the websites from the webmaster’s point of view before they start reading the user comments.

The Firefox add-on Google Sidewiki Client adds the full Google Sidewiki functionality to the Firefox web browser. Google Sidewiki information are added to a new sidebar which can be displayed by pressing the Sidewiki button in the status bar.

Users of the add-on can read the reviews and notes that have been posted by Google users about the website they are on. A little bit unfortunate is that the information are not automatically refreshing. The information are only refreshed if the button in the status bar is pressed again. This needs to be done for example when switching tabs or loading new links in the active tab that lead to other pages or websites.

Users who are logged into their Google account can submit their own reviews of the website, express their opinion about other reviews by voting for or against them, share reviews or report abusive reviews. It is basically the complete Google Sidewiki client in the Firefox sidebar.

The add-on is in an early stage which becomes apparent in two key areas. The first is the already mentioned auto-refresh that is missing. This makes the add-on cumbersome to use. The second are the missing controls in the sidebar. It is not possible to go back or forth and the login screen breaks the layout of the sidebar.

Interested users can download the Firefox add-on from the Mozilla website where it is available for all Firefox 3.x versions.

Google Sidewiki allows Google Toolbar users to leave comments about any website or page that they are visiting. Comments that have been left by other users can be read by anyone but only users who are logged into a Google Account can leave comments.

Users can rate comments and only the most popular comments are displayed initially with the option to look at the rest of the comments on the next page. The Google Sidewiki team has released a video that is showcasing the functionality of it.

One of the problems that these kind of programs are facing is abuse of the system. Google tries to combat abuse with the rating system. It remains to be seen if this is good enough to keep internet marketers and spammers away from manipulating comments on popular websites.

The other problem that could turn down many users is the exclusive integration in the Google Toolbar. Users who do not want to install the toolbar can still read comments by using a method described at Digital Inspiration. Google Sidewiki can be downloaded at the Google website. It is compatible with Microsoft’s Internet Explorer and Mozilla Firefox.

Update: Google has discontinued Sidewiki. The service is no longer available. There does not seem to be a comparable service.