This library (or plugin or whatever it should be called) extends Microsoft Ajax by offering easy client side support for cookies. Not much to say about it - the code to use it in your project looks like this:
You can then manage cookies totally serverside by calls like:
This Cookie manager demo (inside CookieSolution.zip download) shows you how it works. It contains the exact demo you can see here - Demo of ASPCode.net.CookieManager
The other download is just the javascript file.
The code is free to use, i.e dual licensed under GPL and MIT. See the scriptfile header.
I have borrowed a lot of code and ideas from Klaus Hartl and his JQuery cookie plugin.