For most of June 2009 CKnow had an AddThis button in the footer of the site. This button allowed users to highlight pages on various bookmarking sites. We did not get many uses but it was an interesting diversion.
Today (10 July 2009), however, I removed all instances of the button from the site and cancelled the account. Why? They started inserting a Flash tracking object to the site without prior warning or permission. Now, to be fair, this object might have been mentioned either directly or by implication in the various agreements they have but I usually read those and don’t recall reading about it.
Even so, since the button did not include this Flash tracking when I first put it on, the change was an unpleasant surprise. I noticed it when viewing the site and NoScript (a Firefox add-in I can’t live without) blocked the call to the clearspring.com website.
If you use AddThis, you might want to watch your website and consider if this sort of action agrees with you and then either leave their button or not as you decide.