PublicAPIs - Explore the largest API directory in the galaxy
Vacuum Data - Instant access to all* open data from a single place
API List - A collective list of APIs. Build something.
Mapsense - The API for data-driven mapping
API for Product Managers - The A to Z of APIs for product managers
OpenStreetMap - OpenStreetMap is a map of the world, created by people like you and free to use under an open license.