Yahoo! Anti-Spy
I believe in giving credit where credit is due. I've long been a fan of Yahoo!. I've had an email account with them since 1995 and I use their Instant Messenger and tool bar companion. Today, they unvieled Yahoo! Anti-Spy which is integrated with their new Yahoo! Toolbar. From what I can tell thus far, the Yahoo! Toolbar is what they used to refer to as the Yahoo! Companion simply re-branded with their new Anti-Spy application. The bottom line is this new download will find and remove spyware and other unwanted programs while acting as an effective pop-up blocker, search tool and personalized bookmarker.
I think this is a very handy tool, especially if you're already using other Yahoo! services. You can download it here.