TPB no longer uses torrent files as their primary distribution mechanism. Torrent files were already small, but now they use magnet links which are basically just a SHA1 hash and a URL for a tracker. The tracker isn't strictly necessary.
Here's a fun trick: Make a plaintext file containing "Hello world" (maybe lowercase, maybe either will work). Take its SHA1 hash. Paste that into the Transmission "Open torrent address" dialog (edit: It looks like you can only directly paste hashes into the web dialog. You can still craft a magnet link manually). Give it like 5-10 minutes. Through the magic of DHT, you will soon have a brand new copy of the "Hello World" text in your downloads directory.
Here's a fun trick: Make a plaintext file containing "Hello world" (maybe lowercase, maybe either will work). Take its SHA1 hash. Paste that into the Transmission "Open torrent address" dialog (edit: It looks like you can only directly paste hashes into the web dialog. You can still craft a magnet link manually). Give it like 5-10 minutes. Through the magic of DHT, you will soon have a brand new copy of the "Hello World" text in your downloads directory.