This works best if you have a twitter account, but not necessary.
But you will want to have the name of a twitter account you start with.
For example my twitter ID is kelvinbrown
So go to Kelvin Brown Stats & Rankings (kelvinbrown) | Twitterholic.com
It will tell you my twitter rank within my community,
Kelvin Brown is ranked 27th in their location on twitterholic! (by followers in 'Washington DC')
And so what you want to do at this point is click on my community ( washington, DC) .
Not all locations are created equal.
The locations are input by many different people with no standard to names.
So, you can experiment with changing the location. And always end the url with a ( / ).
At this point you see the top 100 to 500 twitters, in the community. Now, you can click on the users names and check the links in their bios to see if they are someone you wish to follow.
And I am sure that you can find many other uses for this data.
Hope it helps.