What is your experience about using tabs/buttons that are fixed to the left or right on the browser window? (see an example to the right on this site) They are usually used for feedback forms or social media buttons.
My suspicion is that people do not look so far to the sides. When experimenting with the placement of ads and social media buttons it's better to position them as close to the content (such as an article) as possible.
Do you believe that placing links at those positions is effective?