Yahoo recently released PingBox…
a new application that once embedded into your blog, website or social network page, lets visitors IM you anonymously (or they can identify themselves) without needing to download or even sign into Yahoo! Messenger. The good news is you’re anonymous too; visitors to your page never see your Yahoo! ID. Pingbox is great for giving your site/page/profile visitors a quick way to chat with you.
Chat privately with visitors on your social network profiles, blog, or website through Yahoo! Messenger
It’s just like Google’s Chatback which i already have installed here in my blog (check my sidebar).