This document discusses tools and projects for digitizing and georeferencing historical maps on the web in an open and collaborative manner. It presents examples like Gutenkarte for browsing geographic texts, and the NYPL Map Rectifier and Digitizer. It also covers best practices for public editing, versioning, and resolving disputes on collaborative projects. Finally, it promotes open access to historical maps and building a shared database through crowd-sourcing with tools like Whooms and Mapwarper.