BlueZ is Bluetooth protocol stack for Linux. It provides supports for core Bluetooth layers and protocols, and has flexible, efficient, and modular architecture. It has many interesting features, like support for multiple Bluetooth devices, multithreaded data processing, hardware abstraction, and standard socket interface to all layers. BlueZ is part of the official Linux kernel (since 2.4.6).
TUN provides packet reception and transmission for user space programs. It can be viewed as a simple Point-to-Point or Ethernet device, which instead of receiving packets from a physical medium, receives them from a user space program and instead of sending packets via physical media writes them to the user space program.
VACUM is framework for video analysis and comparison. It provides flexible input handling, an image processing library, and tools for objective and visual measurement of the video quality. It includes a video player that can play multiple video files side-by-side, compare video frames and generate "visual diff", display PSNR values, and single step through the frames.