I've been seeing a lot of good Google Maps recently that are using Google Fusion Tables to store the map date. Google Maps with Fusion Tables can contain bounding box and radius spatial queries. These features are built into the Google Maps API V3.
As well as these official features a number of developers have created some nice workarounds to add other features to Fusion Table driven Google Maps.
Map with Sidebar (demo map now removed)
This experimental map from the Natural History Museum includes a great sidebar that is also driven by Fusion Tables. Each entry loaded into the sidebar is also an active link which will open the information windows in the Google Map.
Custom Map Markers
This Google Project Hosting example uses the Google Visualization API with Fusion Tables to create a Google Map with custom map markers. Fusion Table maps use the default Google Maps map markers but this code example provides a neat hack to allow you to replace these with your own map marker images.
Animating Fusion Table Data
This is my own attempt to use Fusion Tables to create an animated Google Map. The map animates through the over 800 bombs dropped on London on the first night of the London Blitz.
There is an ugly flicker at the moment when each new marker is added that I'm working on trying to overcome.
Here is a Fusion Tables map that includes a two thumb time slider that allows you to load data onto the map from a specified date range. The Random Markers blog includes a couple of other examples of Fusion Table generated maps with time-line slider controls.