OSM Tasking Manager is a mapping tool designed and built for the Humanitarian OSM Team collaborative mapping. The purpose of the tool is to divide up a mapping job into smaller tasks that can be completed rapidly. It shows which areas need to be mapped and which areas need the mapping validated.
This approach facilitates the distribution of tasks to the various mappers in a context of emergency. It also permits control of the progress and the homogeneity of the work done (e.g. elements to cover, specific tags to use, etc.).
Some resources to help you start using the Tasking Manager:
OSM Tasking Manager is an open source software.
Feel free to report issues and contribute.
The application code is available on github.