Personalization service providers?

Anyone seen a software package or ASP that provides personalization features 
to a web site?

Examples of what I'm talking about are my.yahoo.com, my.netscape, etc.  
Basically, you register for a service like this by filling out a form that 
tells the server what kinds of information you'd like to see everytime you 
visit the page.  The user can elect to let the page load automatically 
(without a password) or logout when done.  This would be done with a cookie, 
of course.

Without having to worry about "how" this type of thing is achieved, I'm 
interested in knowing someone/someplace that has taken much of the heartache 
out of the process of developing such a service.

Got any suggestions?

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