libnodelay is an LD_PRELOAD library for disabling Nagle's algorithm. Disabling Nagle's algorithm can result in a performance improvement for latency-sensitive applications that use TCP. Using the library may be easier than digging through a mess of code and confusing or obscure configuration options.
mmq plays arbitrary audio files gaplessly and continuously without needing a predefined queue. mmq is an exercise in minimalism, so it is more about avoiding needless features than anything else. mmq may be used standalone or managed by a larger application. mmq is only configurable at build time. Currently, FLAC decoding and SALSA-lib audio output support are implemented.
pcu is a set of simple command-line utilities to expose the posix_fadvise and mincore syscalls. pcu-fadvise gives the kernel advice on the access pattern for files. This advice can affect all processes by all users accessing those files. pcu-mincore is used to determine which parts of a file are in cache. These utilties are targeted for Linux 2.6, but may work on other operating systems that support the mincore and posix_fadvise syscalls. mincore is not a part of POSIX, and posix_fadvise is uncommon despite being specified by POSIX.
Unicorn is a Unix and LAN/localhost-optimized fork of the Mongrel HTTP server. It takes full advantage of functionality exclusive to Unix-like operating systems. It will reap and restart workers that die from broken apps, and there is no need to manage multiple processes yourself. Load balancing is done entirely by the operating system kernel. Requests never pile up behind a busy worker. The server does not care if your application is thread-safe or not, as workers all run within their own isolated address space and only serve one client at a time. All Rack applications are supported along with pre-Rack versions of Ruby on Rails via a Rack wrapper. It also supports atomic log cycling, nginx-style binary re-execution without losing connections, before_fork and after_fork hooks, and optional copy-on-write-friendly memory management.