storm-contrib is a community repository for modules to use with Storm. These include a variety of spouts/bolts for integrating with other systems (Redis, Kafka, MongoDB, etc), as well as code for common tasks a Storm developer encounters.
For more information about Storm itself, see the Storm GitHub repository.
storm-contrib is organized as a "super-project" with a sub-folder for each module. Each module is distributed independently and module owners are responsible for distribution.
If you're interested in contributing a module to storm-contrib, send an email to the Storm mailing list. You will then be given commit rights to storm-contrib. The advantage of having your module be part of storm-contrib instead of your own project is more visibility for your code. However, if you'd rather maintain your module as its own project that's fine too!