jReviews :: Customer support forum

I'm not sure what to call it?? but I'm making a travel website and I want a field for every city in the world. This makes for a very long select list and i think it is too confusing. a great idea is to have a field that narrows down the results as you type (look at www.tripadvisor.com) users could then add new cities in the backend. Not sure how difficult this is or if its possible but would be an awesome feature.