MesoWest's VoroWeather Map is an interesting Voronoi tessellated weather map of the US.
The map uses weather observations from around 2500 weather stations across the United States. Each station is marked on the map with black dots. Every area of the country is then shaded on the map based on the weather readings of the closest station. The Voronoi Tessellation for each station has been calculated and the shapes are colored based on the temperature, relative humidity, or wind gust observation.
You can change the weather data shown on the map using the 'variables' button. Click on a tessellated shape on the map and you can find out the closest weather station's name, elevation, and observed values for temperature, relative humidity, and wind gust.
If you are interested in using Voronoi tessellations on an interactive map then you should check-out Chris Zetter's tutorial on how you can go about Building a Voronoi Map with D3 and Leaflet. The tutorial is accompanied by a demo map of UK supermarkets.
The Supermarket Voronoi Map is a map which divides the UK into a number of regions. Each region contains one supermarket, where all the locations within each region are closer to that supermarket than any other.
Using supermarkets for the demonstration map is a great idea, as it really helps to convey the usefulness of Voronoi maps. Shoppers can use the map to find their nearest supermarket. You can even select an individual chain of supermarket to find the nearest branch. For example you could use the map to find your nearest Waitrose.
Biking from Place to Place is a neat visualization of Chicago's bike share network. The map uses a very clever Voronoi heat map technique which allows you to find out the number of bike trips from any bike station and view the most popular destinations from each station.
Select a bike station on the map and you can view a heat map showing the most popular destinations from that station. The map provides some interesting insights into the travel patterns of Divvy bike users. For example, if you select a bike station along Lake Michigan you quickly notice that most Divvy users borrow bikes here to cycle to other bike stations along the lake shore.
The heat map overlay uses an interesting Voronoi map technique which allows you to find the nearest bike station to any location. If you point to any location on the map the nearest bike station is automatically selected for you and the Voronoi heat map overlay also shows you the areas around the destination stations. This provides an insight into the likely final destinations of the bikes' users.