While I've never been a fan of toolbars of any kind, the critical security issue for the Linked In IE tool bar is now fixed

LinkedIn IE Toolbar - Critical Security Update Available
http://www.scmagazine.com/us/news/article/673669/linkedin-fixes-critical-bug/

QUOTE: "Business networking site LinkedIn has remedied a dangerous zero-day vulnerability in its Internet Explorer toolbar, one day after researchers went public with the exploit code. The mandatory fix "was pushed out to all of our users" on Wednesday, Mario Sundar, community evangelist at LinkedIn, told SCMagazine.com today. "The fix is required for users; otherwise the toolbar shuts down"..." 

LinkedIn IE Toolbar - Critical Security Issue
http://secunia.com/advisories/26181/