Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
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.
Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
4Pane is a four pane detailed-list file manager for Linux. It is designed to be fully-featured without bloat, and aims for speed rather than visual effects. In addition to standard file manager things, it offers multiple undo and redo of most operations (including deletions), archive management including 'virtual browsing' inside archives, multiple renaming/duplication of files, a terminal emulator, and user-defined tools.
Quassel IRC is a modern, cross-platform, distributed IRC client, meaning that one or more clients can attach to and detach from a central core, much like the popular combination of screen and a text-based IRC client, but graphical. In addition to this unique feature, it aims to be a comfortable chatting program.
X File Explorer (Xfe) is a filemanager for X. It is based on the popular, but discontinued, X Win Commander. Xfe is desktop independent and is written with the C++ Fox Toolkit. It looks similar to Windows Commander or MS-Explorer, and is very fast and simple. It features file associations, the ability to mount/umount devices, a directory tree for quickly changing directories, the ability to change file attributes, automatic registry saving, the ability to view/create/extract compressed archives, and much more.
eSpeak for Android is a port of the eSpeak Text-to-Speech synthesiser to Android, supporting 75 languages and accents. It is based on the eyes-free version, but with improved language selection and language name display, support for accents and special characters, improved handling of speech rate and pitch, support for MIPS-based devices, and improved support for SSML.