AJAX forms

Hi *,
I'm trying to build a form for editing user's accounts, and the problem I'm facing actually is how to add instant messengers accounts.
My idea was to use a link_to_remote to add a select and a text field every time the user adds a new account using AJAX, but I need a way to keep track of other accounts (a user has_many im accounts).
How do you people solve the problem of having an unknown number of similar entries inside a form and still having a clean params variable ?

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