Have you ever reached a particular website and found it really hard to find the information you were looking for? Have you ever needed a bit of help from friends to work the checkout on a website? What about letting others know how great you think a site is – did you want share your feedback with other visitors?

Thanks to the Google Sidewiki, you can now do all of these, and much more besides. And you can also read the notes and comments left by other visitors to a website.

Launched a few weeks ago, the Sidewiki lets you add helpful information alongside any webpage. The Sidewiki looks like a browser sidebar, where you can read what others have said, and also write your own entries.

If a webpage has lots of entries they are ranked according to lots of ’signals’ which mean that those considered most useful stay at the top. The ranking system takes into account feedback that you and other users have given, and previous entries you’ve made. The entries are ranked in real time. You can read more about how they’re ranked on the Google Research Blog.

If you make a comment about a particular web page, the Google sidewiki will also display those comments against webpages that contain the same snippet of text.

Let’s say you were leaving comments about Gordon Brown’s party conference speech, on a webpage that actually included the text of the speech: your comments made on one website could also be visible on other websites displaying the same bit of Brown’s speech.

The sidewiki also pulls in posts from blogs and other websites that discuss the particular webpage, so you can see what other people are saying about it even if their comments reside elsewhere.

At the moment the Sidewiki is a feature on the Google Toolbar for Firefox and Internet Explorer.

If you’re interested you start using the Sidewiki by visiting google.com/sidewiki to download Google Toolbar with Sidewiki.

If you’re a website builder, this feedback is a potential goldmine of information. We’re going to be able to get live feedback from our website visitors about what they think of our website. They will hopefully point out where they think we’re going wrong, and what we need to do to fix it.

Do you think it’s a good idea to allow anyone to comment on any webpage? Would you be happy to read the feedback on your site? As an experienced web user, are you happy to share your feedback? Leave a comment below!