Olark provides a real-time IM customer service tool for websites or blogs, allowing visitors to have real-time conversations with site owners or bloggers through this window.
The predecessor of Olark was hab.la, which is as well-known as Plugoo. It specializes in providing a real-time chat widget for websites or blogs. When your IM account bound to Olark, such as Gtalk, is online, the visitors to your website or blog can chat with you in real-time on your site or blog, and then you can interact with the visitors via Gtalk.