Interactive zip code map

Hello,

I am looking for an interactive map that will display the entire US by
State, County and zip code. I need to be able to modify the colors of
some zip codes in real time based on user feedback and I need to know
what zip code a user clicked on. The idea is that each user can select
as many zipcodes/counties as they want and to change their preferences
for each zipcode.

I have installed geoserver and was able to add the Census bureau Tiger
zip code shapefiles to it, but I am not quite sure where to go to
next. When a user clicks, is there a way to know that he clicked on a
specific zipcode or do I have to send the coordinates back to server
to get a reply?

If there is an easier way or a product already designed to do this
please let me know.

Any help is much appreciated.

Thanks!

-oms