JIRA integrated with Pivotal Tracker.
JIRA allows for tickets. It gives JQL filter ability for search. Gives ability to share tickets between groups. Gives ability for workflow diagrams, history, transitions, comments, etc. Gives ability to view reporters, assignees, implementers. For each ticket there's ability to add Comments, Attachments, Attach Screenshots, Link, Clone, Resolve Issue. JIRA provides a very nice layout of the current ticket state.
Pivotal Tracker allows "velocity" management of project for Agile Development. Useful for PMs and developers. Provides graphs, charts. Provides ability to integrate JIRA's tickets into its project. Provides a dashboard with projects. Provides real-time velocity graphs. Provides a number of views within each project including Current, Ice Box, My Work. Each JIRA ticket can be a "Story" in PT. Each story goes through Start, Finish, Deliver, Accept/Reject, and Rejected stages for SDLC. Each story gives ability to Add Task, Comments, Attachments, and Upload Files.
JIRA workflow 
Pivotal Tracker workflow
