GNUnet is a peer-to-peer framework with focus on providing security. All peer-to-peer messages in the network are confidential and authenticated. The framework provides a transport abstraction layer and can currently encapsulate the network traffic in UDP, TCP, HTTP, HTTPS, or direct 802.11 (WLAN). GNUnet supports accounting to provide contributing nodes with better service. The services built on top of the framework include anonymous file sharing and a virtual network providing IPv4-IPv6 transition via protocol translation over the P2P network.
aria2 is a utility for downloading files. The supported protocols are HTTP(S), FTP, BitTorrent, and Metalink. It has a powerful segmented downloading ability, downloading a file from multiple sources and multiple protocols and utilizing your download bandwidth to the maximum. It supports downloading a file from HTTP(S)/FTP and BitTorrent at the same time, while the data downloaded from HTTP(S)/FTP is uploaded to the BitTorrent swarm. Using Metalink's chunk checksums, aria2 automatically validates chunks of data while downloading a file like BitTorrent.
Podget is a simple podcast aggregator optimized for running as a scheduled background job (i.e. cron). It features support for downloading podcasts from RSS and XML feeds, for sorting the podcasts into folders and categories, for importing podcast URLs from iTunes PCAST files and OPML lists, automatic M3U and ASX playlist creation, and automatic cleanup of old podcasts. It also features automatic UTF-16 conversion for podcasts hosted on Windows servers.
GroupServer is a Web-based mailing list manager designed for large sites. It provides email interaction like a traditional mailing list manager but also supports reading, searching, and posting of messages and files via the Web. Users have forum-style profiles, and can manage their email addresses and other settings using the same Web interface. It has supports features such as Atom feeds, a basic CMS, statistics, multiple verified addresses per user, and bounce detection, and is able to be heavily customized.
F*EX (Frams' Fast File EXchange) is a Web based service for sending very big files from one person to another. The sender uploads the file to the F*EX server and the recipient automatically gets a notification email with a download URL. Files are automatically deleted after download or an expiration date. The recipient and sender only need an email program and a Web browser. Sending to multiple recipients needs storage on the server only once. In contrast with other file transfer services, it has no file size limits at all and comes with shell tools for scripting up/downloading.
SaluSafe is an encrypted email, chat, and file storage and sharing system. Your email and files are highly encrypted end-to-end, and cannot be intercepted by any third party. It was built from the ground up for security via strong cryptography, and is not just another security wrapper on top of an existing email solution.
gPodder is a Podcast receiver/catcher written in Python and pyGTK. It manages podcast feeds for you, and automatically downloads all podcasts from as many feeds as you like. If you are interested in Podcast feeds, simply put the feed URLs into gPodder and it will download all episodes for you automatically. If there is a new episode, it will get it for you. It supports download resume, if the server supports it.