Most of you probably already know about Wikimapia, but for those who don't yet, give it a try. It's basically a mashup of Google Maps where anybody can label some features on the map, such as buildings, roads, parks, businesses, museums, stadiums, etc.
It works anywhere in the whole world, but the link I gave centers it right on Fountain Square in the heart of downtown Cincinnati.
Very useful if you want to figure out where things are or what is close to where you'll be staying.
For those of you who live in Cincinnati, please start adding/correcting notable features, buildings, and attractions. It only works if everyone chips in!