In a very short space of time Windows Desktop Search has become the tool I use most often while at my PC. If you don't have it yet you can download it for free from http://www.microsoft.com/windows/desktopsearch/enterprise/default.mspx.
With a bit of registry tweaking you can also customise this tool to allow you to search across SharePoint Portal Server sites or against specific external websites.
And you can even add shortcuts to your favourite sites so that you can access them quickly straight from your desktop. For example, by typing @#ms,http://www.microsoft.com into the Desktop Search box on your desktop you'll add a shortcut that will allow you to launch your browser straight to www.microsoft.com simply by typing #ms into the Windows Desktop Search box. Very handy!
If you want to get fancy, now try a shortcut like @#efred,mailto:email@example.com that will allow you to start composing an email to Fred (using the fictitious email address firstname.lastname@example.org) simply by typing #efred in the Windows Desktop Search box. Or if you want to instantly email a group of people try setting a shortcut like @#eteam,mailto:email@example.com;firstname.lastname@example.org;email@example.com. Again, very handy!