Show data based on dropdown

Hello,

I’m searching for a plugin(?) which can present data based on a drop-down (select) list box.
For example, this plugin could be utilized as a “store locator” where the site’s visitor clicks on the drop-down list, selects a city name, and get in return a list of stores located in the selected city. However the plugin should be flexible and able to support different kinds of data.
I would also prefer it if the data is saved in a separate DB table, as opposed to using posts and post types.

Hope you can help.

[No bumping. If it’s that urgent, consider hiring someone.]