One way you could do this is create a webform (or modify an existing one) and add all the mailing lists you have to it, something like this -
http://screencasteu.worldsecuresystems.com/Mihai/2012-08-06_1119.png
Then, based on the value of the {module_homestate} for example check the appropriate mail listing checkbox using javascript, a switch statement - http://www.w3schools.com/js/js_switch.asp would allow you to compare the output of {module_homestate} with a list of known states.
You can also do this at the time the user subscribes to your system, the mechanism is simmilar, only this time you have to decide what mailing list to check depending on what the customer enters in the "State" text box.
One other thing you might want to do is enable the automatic opt-in feature - usually the user is sent an email adking him to confirm he wants to subscribe to that mailing list. You can bypass this and make the experience seamless to the user by adding "OPTIN=true" to the action of the form, see this thread - http://forums.adobe.com/message/4425547 for more details on how to add this functionality.
