Google Chat in ASP.NET Application
I think the sane approach is to open an iframe that talks to a dynamic page. A dynamic page will be automatically updated by two or more clients and constantly send / read from a table that stores session IDs, timestamps, username (or IP), and chat messages. The session id will match the id of the dynamic page and bob is your uncle.
I'm sure there are various implementations floating around, but I'd like to control this myself. No user accounts are required, if you set them up correctly, thought finding other users could be a problem without accounts.
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There are many good embeddable chat widgets that you can easily embed into a page that does all the work for you.
I've tried several of them listed in the link above (mainly MeeboMe and Geesee) and you have no major complaints. With this multitude of options, you should find the one that suits your needs. Most don't even require a login.
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