A good place to search for local twitter users is at Twellow, an application that serves as the yellow pages of Twitter. First, register for free. This will let you look at more information about a person as well as follow them. Second, type Louisville into the Search box. You'll see a listing of all Twitter users that have Louisville either in the Location or Bio section of their profiles. Scroll through the pages of users and when you find someone interesting, click on their name to see their complete profile and part of their twitter stream.
Now all you have to do is click Follow on their profile and they'll be added to your Twitter account in the Following List. Their tweets will show up on your account page in the Twitter stream.