rocknbil - 4:03 pm on Sep 16, 2010 (gmt 0)
They are only able to select from a drop-down, pre-populated list generated from the db.
Good, now you'll have
<option value="1234">Beverly Hills</option>
<option value="Beverly Hills">Beverly Hills</option>
What if their region isn't listed? You let them build the list for you by offering an "other region" field which you can *temporarily* store in a table somewhere, associated by the listing ID. When it comes up, if these are moderated (which I'm guessing they should) you can add the new region to your regions table and update their record.