The Google toolbar 1.1.58 and earlier allows remote web sites to monitor a user's input into the toolbar via an "onkeydown" event handler.
https://exchange.xforce.ibmcloud.com/vulnerabilities/10054
http://toolbar.google.com/whatsnew.php3
http://sec.greymagic.com/adv/gm001-mc/
http://archives.neohapsis.com/archives/ntbugtraq/2002-q3/0066.html