Below are just some of the APIs that are out there on the web for you to use.  Use what works best for you, and let us know if you find more that should be added here.

Category	Organization	Description	URL
Agriculture	eLeaf	Demo data sets for vegetation, water and CO2 intake	http://demo.eleaf.info/eleafchina
			http://demo.eleaf.info/eleafindia
		API for ARCGIS Server	http://demo.eleaf.info/ArcGIS/rest/services
		API documentation	http://resources.arcgis.com/content/arcgissdks/10.0/about
			http://links.esri.com/help/rest
			http://links.esri.com/help/soap
Data.gov	Data.gov	API to return demographics by coordinates	http://explore.data.gov/Information-and-Communications/Demographics-API-by-Coordinates/jya9-8j2b
Energy	Genability	Real-time, accurate and comprehensive electricity pricing, NA-wide (residential and C&I)	http://developer.genability.com
	Tendril	Residential energy usage and cost, price programs, device control and messages	http://www.tendrilinc.com/developers
	AMEE	Categories and data items description	http://discover.amee.com
		Developer guide	http://www.amee.com/developer
		SDK’s	http://www.amee.com/developer/sdks
Geolocation	Infochimps	Geo APIs	http://www.infochimps.com/apis/geo
	Microsoft	Bing Maps Tile System	http://msdn.microsoft.com/en-us/library/bb259689.aspx
	MapTiler	Graphical application for online map publishing	http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/
General	Microsoft Azure	Wolfram Alpha – Query engine	https://datamarket.azure.com/dataset/aec04387-0110-4f27-8766-faa70a8f75c0
Sustainability	CSRHub	API	http://www.csrhub.com/content/api-methods
		Data Sample	http://www.csrhub.com/subscription_sample
		Widget sample	http://www.csrhub.com/content/sustainability-rating-widget
Transportation	GTFS data exchange		http://www.gtfs-data-exchange.com/
	GTFS-realtime	Documentation	https://code.google.com/transit/realtime/
	Google maps traffic layer	Documentation	https://code.google.com/intl/xx-elmer/apis/maps/documentation/javascript/overlays.html#LayersOverview
	Nextbus	muni, AC transit and more	https://www.nextbus.com/xmlFeedDocs/NextBusXMLFeed.pdf
	BART	API	http://www.bart.gov/schedules/developers/api.aspx
	BART GTFS-realtime		http://www.bart.gov/dev/gtrtfs/tripupdate.aspx
	Tri-met GTFS-realtime		http://developer.trimet.org/GTFS.shtml
	MBTA GTFS-realtime:		https://www.mbta.com/rider_tools/developers/
	SFPark	Real time parking availability and pricing API	http://www.datasf.org/story.php?title=sfpark-real-time-parking-availability-and-pricing-api
	Google maps Bike and Walk directions API:	Documentation	https://code.google.com/intl/xx-elmer/apis/maps/documentation/directions/#TravelModes
	Bikesy Bay Area Bike directions	API	http://blog.bikesy.com/api/
Weather	Weather Underground	API	http:// http://www.wunderground.com/weather/api/