Jira Plugins @ SourceForge is a development project for development of plugins to Atlassian JIRA.
Jira can be widely extended with different kinds of plugins. The main goal of this project is for users/developers of Jira to share plugins developed in-house. This might be due to lack of progress in requests to the core Jira developers regarding new features or requests rejected by core Jira developers, but yet considered useful to others.
For further reading on development of Jira Plugins, go here.