we have a nationwide dealer locater website home page -
we are looking for a way to do a small popup for our particular services in our city based on se keyword search returning home page of locator service - offering a chance for people to click right to our www site

example:

our dealer locator home page is for nationwide widgets -
we get many se hits for city and widget keyword searches -
when a www user types in widgets 'mycity' into browser - upon presentation in se returns and the clicking of my home page from the se refer of "mycity" to nationwide dealer locator home page i would like to show a popup message/banner promoting my particular - keyword based "mycity" when my site is clicked on from se returns
how could this be done?

example2
se search for widgets chicago - my home page pops up plain

example3
se search for widgits mycity - my home page pops up welcome message for refer of 'mycity' (please click here for the 'mycity' home page - sort of thing)

any thoughts would be much appreciated!

many thanks