A lot of advertisers do local advertising to increase the awareness of the product. Local media is also used to launch a product in some particular city. Various media forms can be used like print, newspapers, radio etc.
If the advertising is driving to a vanity URL or website, it is very easy to measure the lift from the advertising efforts. With the use of web analytics tools like Omniture, Webtrends, Google Analytics it is possible to measure the number of visitors to the site from a particular geo (country, city etc). So, if there is a lift in the number of consumers visiting the site from the city where the advertising is live, it is a clear indicator that the advertising is working and driving consumers to the website.
As mentioned in my previous post, a pre-post visitors/day would help evaluate the effect of the online advertising.