LibU is a multiplatform C library that comes under a BSD-style license. It includes many interdependent modules for accomplishing several tasks: memory allocation, networking and URI parsing, string manipulation, debugging, and logging in a very compact way, plus many other miscellaneous tasks. It has a small footprint (about 70KB for the default configuration), it is modular, and it has a multiplatform nature, making it an ideal candidate for embedded systems. KLone is an example of such usage.
DeforaOS Browser is a file browser for the DeforaOS desktop. It depends only on GTK+ 2 and the DeforaOS System and Desktop libraries. It supports browsing with multiple views, MIME type application association, and file manipulation. It also features a program to display file icons on the desktop, which is useful with window managers like WindowMaker or Fluxbox.
skipfish is a high-performance, easy, and sophisticated Web application security testing tool. It features a single-threaded multiplexing HTTP stack, heuristic detection of obscure Web frameworks, and advanced, differential security checks capable of detecting blind injection vulnerabilities, stored XSS, and so forth.
Hybris (hybrid scripting language) is a dynamic scripting programming language created to help developers to automate everyday procedures in a easy and fast way. Although is a high level language, Hybris supports dynamic library linking, native C function calls, and a lot of other low level functionality.