QMentat helps you practice mental arithmetic. It uses arbitrary-length fixed point arithmetic, and can handle any size numbers, only limited by the size of your screen (and in the case of division with an integer result, the speed at which the number can be factored). It is also quite configurable, allowing you to tailor the questions to your needs.
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.
The YB.ORM library aims to simplify writing C++ code that has to deal with SQL databases. The goal is to provide a convenient interface like SQLAlchemy (Python) or Hibernate (Java). The library itself is cross-platform and supports a variety of SQL dialects: SQLite3, MySQL, Postgres, Oracle, and Firebird. Integration with Boost, Qt4, and wxWidgets is built-in. In a typical usage scenario, you would describe your database schema and table relationships in a simple XML-based format, generate SQL code to populate database schema with tables, generate C++ classes, add application-specific logic to the classes, and use these classes in cooperation with the Session object to query objects from the database, create new or modify/delete existing objects, or link and unlink objects using relations. Simple serialization to XML is supported along with connection pooling.
ChaiScript is an embedded scripting language designed from the ground up to directly target C++ and take advantage of modern C++ development techniques. Being a native C++ application, it has some advantages over existing embedded scripting languages. It uses a header-only approach, which makes it easy to integrate with existing projects. It maintains type safety between your C++ application and user scripts. It supports a variety of C++ techniques including callbacks, overloaded functions, class methods, and STL containers.
4K Video Downloader is a video and audio downloader for YouTube, Vimeo, Facebook, Dailymotion, Metacafe, and other video-sharing services. It features video quality up to 4k resolution, FLV, MP4, and MKV support, extraction of audio to the MP3 format, and a "Smart Mode" for fast downloads.
ImageVis3D is a volume rendering application specifically designed to render large data sets. This is achieved by splitting the data set into multiple levels of detail (LoD), with each level itself decomposed into multiple bricks (atomic rendering primitives). Interaction occurs at the coarsest LoD, which can be rendered instantaneously on almost all modern systems. After a configurable delay, ImageVis3D will successively render finer levels of detail, until the data are visible at their native resolution. Volume rendering, as the name implies, is a technique for rendering scalar volumes of data. The rendering method allows one to see "inside" a data set, allowing the user to understand the inner three-dimensional structure of the data.
Arx Libertatis is a cross-platform, open source port of Arx Fatalis, a 2002 first-person role-playing game developed by Arkane Studios. Arx Fatalis features crafting, melee and ranged combat, and a unique casting system where the player draws runes in real time to effect the desired spell. The Arx Libertatis source code is based on the publicly released Arx Fatalis sources. This does however not include the game data, so you need to obtain a copy of the original Arx Fatalis or its demo.