Recently both Microsoft and Yahoo! released Toolbars akin to Google's Toolbar. All three companys provide pop-up blocking and quick searching, but the nice thing about Yahoo! and Microsoft is that their toolbars each have a little icon that informs you when you have new Yahoo! Mail or Hotmail - the advantage of having an email offerring at your portal. Not to be outdone in the art of copying the ideas of others without really adding any benefit whatsoever, Google is planning on launching their own Web-based email system, akin to Hotmail.
Personally, I use GoogleBar, a Google Toolbar clone that is designed for Mozilla and FireBird. (The standard Toolbars for Microsoft, Yahoo!, and Google only work only in IE 5+.) Trillian is nice enough to let me know when I have new Hotmail, so I see no need to start using the Microsoft Toolbar.
You can get Microsoft's Toolbar at http://toolbar.msn.com/, and Yahoo's Toolbar at http://toolbar.yahoo.com/