Searching online, I see lots of people asking for features to have multiple levels of sub-tasks, and proper sub-task functionality (like FogBugz). But I don't know if it's planned in future versions, or if plugins exist to provide this functionality.
Does anyone know?
Hey John, we're working on a plug-in for multi-level subtasks. See details and follow us at http://h4j.almworks.com
As for current solutions, you may use links as a very limited workaround. There are also some hacks to allow creation of sub-sub-tasks, see comments to http://jira.atlassian.com/browse/JRA-4446