OmniTracker marries the OmniGroup's excellent OmniFocus with Pivotal's Pivotal Tracker.  

Syncing with Tracker requires an API token.  Once configured, OmniTracker will create a folder pattern with a single directory called 'Tracker' which will have sub-directories for the accounts.  Within each account directory will be a project for each of your Tracker projects.

Tracker -> ACCOUNT_NAME -> PROJECT_NAME