Demonoid (a personal favorite of many About.com readers, Demonoid is also a major tracker database that supports thousands of swarms around the globe. Even better, the Demonoid community polices itself by monitoring how much each member actually shares files. ("Leeches" are not tolerated at Demonoid). Note: because new memberships at Demonoid are scarce, you will need to be patient and committed if you wish to join.)