Here's a list of great public trackers, from About.com, and personal experience:
Q. What Are The Good BitTorrent Search Engines?
A. As of October 27, 2006, the 5 Best Bit Torrent search engine sites are listed below. This list is selected from hundreds of reader votes, and voted on each week by a small panel of torrent download users.
The criteria used to evaluate these torrent sites: breadth and depth of database, database currency, ease of use and searching, speed of access, general integrity of files, information provided about the files, information provided on the torrent P2P community, price of membership, and readers' comments.
Obviously, public trackers are less secure than private ones. However, they are a great source for rare downloads.
1. Torrentscan.com (a search engine that searches torrent search engines)
2. Torrentspy (Recently, this site went through a facelift, and it is winning over many new subscribers.)
3. Isohunt (This Canadian database has managed to stave off the threat of one MPAA law suit. Alas, the site is now again being sued by the MPAA as of February, 2006. The site owner is a true libertarian, and needs financial help mounting a defense against the MPAA. Read the details at the Isohunt home page. This is an outstanding torrent database, and P2P users are cheering for its continued success and operations.)
4. The Pirate Bay (Pirate Bay, by readership size, is the most popular torrent search site today. Like Isohunt, Pirate Bay has an immense database of the latest torrents.)
(May 31, 2006 update: The Pirate Bay has been temporarily shut down by Swedish authorities. Details are available on the Pirate Bay home page. This is a sad day for torrent users everywhere.)
(June 2006 update: The Pirate Bay has restarted operations, now that the police have duplicated the PB hard drives for forensic purposes. Enjoy this database while it is still around, folks!)
6. **Special Mention: Torrentportal (Torrentportal has been recommended by many reader emails this May.)
7. **Special Mention: Seedler (was a former member of this list, and has recently become a renewed reader favorite.)
And my personal favorite: torrentz.com
Other Great trackers:
Mininova - Started in January 2005 as an alternative to SuprNova, which went offline at the end of 2004 due to legal issues. Scrape data (amount of seeds/peers) is collected every hour. No adult Material.
Torrent Finder - Indexes 156 Torrent trackers/Search engines.