CallingID Link Advisor verifies the links you see in Firefox and Thunderbird are safe before you follow them. When the mouse is placed over any link a risk assessment and the full details of the site owner are displayed, helping you evaluate the site before visiting it. If the site is assessed as high risk or its owner is located in a 'problematic' country, you will be notified and advised to ignore the link.
CallingID Link Advisor warns you of links to sites that are known as phishing sites; use malicious code; are owned by illegitimate entities; contain or are reached via deceiving links (any link whose destination is different than the one displayed); sites that hide their owners’ identity. CallingID has a database of over 3 million web sites and thousands of new sites are added to the database daily.
CallingID Link Advisor is also available for Internet Explorer and AOL web browsers, Outlook, Outlook Express, Thunderbird, Eudora and Incredimail email clients, ICQ, Google Talk and Yahoo messengers.
You can download Link Advisor for other applications here: http://www.callingid.com/download.aspx