FFTW is a fast C FFT library. It includes complex, real, symmetric, multidimensional, and parallel transforms, and can handle arbitrary array sizes efficiently.It is typically faster than other freely available FFT implementations, and is even competitive with vendor-tuned libraries (benchmarks are available at the homepage). To achieve this performance, it uses novel code generation and runtime self optimization techniques (along with many other tricks).
Isabelle is a popular generic theorem prover developed at Cambridge University and TU Munich. Existing logics like Isabelle/HOL provide a theorem proving environment ready to use for sizable applications. Isabelle may also serve as framework for rapid prototyping of deductive systems. It comes with a large library including Isabelle/HOL (classical higher-order logic), Isabelle/HOLCF (Scott's Logic for Computable Functions with HOL), Isabelle/FOL (classical and intuitionistic first-order logic), and Isabelle/ZF (Zermelo-Fraenkel set theory on top of FOL).
MLton is a whole-program optimizing Standard ML compiler. It generates standalone executables with excellent runtime performance, supports the full SML 97 language, and has a complete basis library. It also has a fast C FFI, source-level time and allocation profiling, and many useful libraries.
PXP is a validating XML parser for the programming language Objective Caml. It strictly implements the full XML-1.0 standard. The XML instance is represented as a tree of objects. It is also possible to access the DTD. PXP means "Polymorphic XML parser" and emphasizes its most useful property: that the API is polymorphic and can be configured such that different classes are used to store different types of elements. PXP contains a user's manual and several example, and has been designed with CGI programming in mind, however is not limited to this field.
sml/nj (Standard ML of New Jersey) consists of a compiler, compilation manager, and libraries for Standard ML. Included are CML (Concurrent ML) and eXene (a toolkit for X based on CML). The compiler produces efficient code for most popular architectures (Intel x86, Sparc, Alpha, Mips, HP-PA, PowerPC) and runs under Unix, Linux, or Windows (95,98,NT).
SwiftSurf is an HTTP proxy that lets you do a lot of things. You can spy, filter, and modify the HTTP requests that your browser sends, as well as the answers it receives. Some of its possible uses include filtering ads, limiting access to a specific domain, or suppressing cookies.
Unison is a file-synchronization tool for Unix and Windows. It allows two copies of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other. Unison can deal with updates to both replicas of a distributed directory structure. Updates that do not conflict are propagated automatically. Conflicting updates are detected and displayed. Unison can communicate through a direct socket link or through an rsh/ssh tunnel. It uses network bandwidth efficiently.