Vuze (formerly Azureus) 4.3
Vuze, originally known as Azureus, is a BitTorrent client written in Java, which makes it rather platform independent.
The Eclipse SWT toolkit is used for providing the user interface functionality.
The BitTorrent protocol is a new way of exchanging or distributing data over the internet. Downloading also means uploading, and the amounts of each are linked, to ensure fairness and rapidity in the spread of the file at hand.
Oracle Java required.