Xvid (formerly XviD) is an open source MPEG-4 video codec, implementing MPEG-4 Simple Profile, Advanced Simple Profile, and Advanced Video Coding standards. It is written in C with assembler optimizations for quality and speed (including MMX, SSE, and 3Dnow! code for i386 and AltiVec for PowerPC), and is especially optimized towards offline, multi-pass compression for storage and archival purposes.
smake is a highly portable 'make' program that makes commands up to date based on rules in Makefiles and on the timestamps of the related files. It implements a complete superset of the features of the classical POSIX/Unix make program. It warns about typical misuse of dynamic macros that prevent portability of makefiles. Its automake features allow you to run scripts to automatically create rules for unknown platforms.
ZSNES is an SNES emulator for i386 machines running Linux, DOS, or Windows. It allows you to play most SNES games on your PC. It also adds several enhancements not present in the original SNES such as filters to improve image quality, savestates to be able to save/restore your game at any time, and more.
Botan is a crypto library written in C++. It provides a variety of cryptographic algorithms, including common ones such as AES, MD5, SHA, HMAC, RSA, Diffie-Hellman, DSA, and ECDSA, as well as many others that are more obscure or specialized. It also offers SSL/TLS (client and server), X.509v3 certificates and CRLs, and PKCS #10 certificate requests. A message processing system that uses a filter/pipeline metaphor allows for many common cryptographic tasks to be completed with just a few lines of code. Assembly and SIMD optimizations for common CPUs offers speedups for critical algorithms like AES and SHA-1.
MPlayer is a movie and animation player that supports a wide range of codecs and file formats, including MPEG 1/2/4, DivX 3/4/5, Windows Media 7/8/9, RealAudio/Video up to 9, Quicktime 5/6, and Vivo 1/2. It has many MMX/SSE(2)/3Dnow(Ex) optimized native audio and video codecs, but allows using XAnim's and RealPlayer's binary codec plugins, and Win32 codec DLLs. It has basic VCD/DVD playback functionality, including DVD subtitles, but supports many text-based subtitle formats too. For video output, nearly every existing interface is supported. It's also able to convert any supported files to raw/divx/mpeg4 AVI (pcm/mp3 audio), and even video grabbing from V4L devices.