PerlShare is a DropBox drop-in to create your own private file sharing "cloud". It consists of two parts; a client and a server. The server part lets you configure a Linux machine to accept PerlShare clients. PerlShare behaves a lot like DropBox. On collisions, for example, it creates conflicted copies. The workhorse for synchronization is Unison, a very reliable piece of software from Pascal Bach.
LibLogicalAccess is an RFID library developed in C++ for Linux/Windows, also available on C# for use on Microsoft operating systems (using a COM wrapper). It provides low-level commands access and high-level generic abstraction for several chips and readers (PC/SC readers like OMNIKEY, STid readers, etc.) on 125Khz (EM4102, HID Prox, etc.), 13.56Mhz ISO14443/ISO15693 (Mifare Classic, Mifare DESFire, HID iClass, etc.), and 433Mhz frequencies.
nf1db is an in memory database engine with SQL and JDBC interfaces. It supports transactions, commands from the SQL-2003 standard, all major data types, a number of functions, default and null values, auto-increments, constraints, primary and foreign keys, set operations, implicit and explicit joins, nested SELECT statements, quantity limits in SELECT statements, and much more.