This is something I feel unsure about. Basically Google toolbar picks up words on a page and creates a link to somewhere else. The example given that causes problems is that of Barnes and Noble and Amazon. You are visiting Barnes and Noble or any book web site for that matter, and you are looking at a page for a particular book. On that page is the ISBN number and Google recognises this and changes it into a link to Amazon. So now they have directed the browser away from one site to another with a possible financial implication. ie: the browser buys the book for Amazon rather than the store they started at. Now this is something Microsoft tried with Smart Tags and quickly dumped due to external pressures. ( More here… )
I personally don’t want anyone messing with my site, any part of it. I want the user to see it as much as possible, as I intended. If I want to add a hyperlink to possible divert the user away then that’s my perogative, so I’m not keen on google changing my text and adding in links, especially as I don’t know where the are going to end up.
However, the user has installed google toolbar and has thus possibly made the decision that they like this process and afterall it’s kind of the principal that the net is built on and great for. The ability to navigate and find more information on a particular subject.
So which is the correct way: allow google to decide what your user sees or deny the user the flexibility?