I found this via Scoble, but take a look at what Paul Rademacher has done with Google Maps and Craigslist!
I could’ve used this a month ago, but I’m pretty happy with the place I found. I used the Apartment People here in Chicago and was pleased with their service. This is primarily due to the agent you get - I’ve heard both good and bad things. Fortunately, my agent (Susan Richter) was excellent. She was able to quickly determine my needs and tastes and show me exactly what I was looking for…even if I can be a little demanding. ;)
I can’t wait!