This page has been moved to the JIRA Knowledge Base. Also see the JIRA Project Management Feature Product Tour.
You may be interested in one (of many!) threads in the forums about using JIRA for Project Management. Here's info on how we are trying to grasp the "Big Picture" of keeping track of all the project versions - by using a Confluence page to pull it all together - kind of like a "portal page".
P.S. this page takes quite a long time to load due to the tree view of all the JIRA Documentation in the left column. Perhaps instead a link to the JIRA documentation page would help? Just a suggestion.
Another plugin for project management can be found at https://www.ibacz.eu/Insight-JIRA-Project-Portfolio.