The "table of contents" for Taskcluster tasks is the
Index. When a task completes
successfully, it is added to the index at an "index route" given by any
task.routes entries that begin with
index.. (Actually, the Queue just
sends pulse messages to well-known exchanges.
The Index listens to
index.* for task completion, and indexes the tasks appropriately).
If you're looking for Gecko tasks, or tasks for another project that reports to TreeHerder, you can use TreeHerder to find tasks. Click on the job in treeherder, then click "Inspect Task".