Azureus – http://azureus.sourceforge.net When people mention file sharing, they automatically think of it as a means to illegally download music, movies and applications. Some member states of the EU have even gone so far as to legislate against the use of file sharing protocols such as BitTorrent. While it is true that a lot of illegal use can occur, BitTorrent still serves a very legitimate function. Many in the Open Source community do not have the ability to host CD images and allow thousands of downloads. Bandwidth is just too costly. But when you need to find a current version of Knoppix or even the 21 CD set of Debian 4.0, there is nothing like using BitTorrent to connect to the hundreds of others that are downloading the same information so that you can obtain a copy faster than any single server can provide.Azureus is my client of choice for BitTorrent downloads. While I am not too fond of the newer client, it retains the capabilities of older versions under the Advanced tab. It is cross platform compatible which means that I can use it on my Mac, Windows or Debian boxes without having to find different applications for each OS.
Filezilla – http://filezilla.sourceforge.net/ While not technically “file sharing”, Filezilla is by far the best application that I have seen for accessing files stored on remote systems. Most people are somewhat familiar with FTP and HTTP downloading. Whenever you click on a link to an application on a web site, you are using one of these protocols to download the file. But these protocols do not offer any form of security. In fact, they send passwords in plaintext which is just wrong.What if you want to securely download a file from your home computer? What if you want to allow your users to access files remotely while not opening up to the world? Filezilla is the only application I would recommend for accessing secure FTP (sFTP) sites. The native drag and drop functionality makes copying websites to your server a breeze. And everything remains encrypted over SSH tunnels.