Weather service. Uses the Open Weather Map web service to provide a 16-day forecast for any city. Enter the name of a city for a forecast of that location. Drill down on a specific day for more details about the weather for that day.
Foreign Exchange Rate service. Uses a free subscription to the Open Exchange Rates service to provide exchange rate information for a large number of currencies. At the free subscription level, exchange rates are only available against the US Dollar. Drill down on a specific currency for the historical exchange rate.
Oxford English Dictionary service.
Various transport related things, using the TransportAPI service:
Bitcoin Exchange services:
Widget stuff.
An example implementation of the Underscore Javascript library.