If you have a web site or a blog, there are quite a few web services using which you can chat with your site visitors. incircles.com
is a new on in that genre.
Just enter your e-mail address, the web page URL and copy paste the code that's generated in your web site to have the chat box appear.
It has PM system, cross site nick retention in a browser (meaning, if you change your nick to say 'x' while using Firefox on a blog, if you visit another site having incircles chat box, your nick will automatically be set to 'x'), and is skinnable.http://incircular.blogspot.com/
is their blog.