I’ve just registered and installed Plugoo here. It works like this (from the FAQ):
On your blog, personal webpage or e-sales site, you set up a Plugoo (very easy to do, by the way !). Visitors on your site can see the Plugoo and type a message in it to send it to you !
This Plugoo is directly connected to your Instant Messenger and forward you in real time all the messages your visitors send you. You answer to the visitor directly from your Instant Messenger, LIVE !
So if I’m online, you’ll see it in the box below. I’ll install it in the sidebar when it moves off the frontpage.