GNU libmicrohttpd is a small C library for embedding HTTP server functionality into other applications. It is reentrant, fast, supports HTTP 1.1, and permits listening on multiple ports. The API is simple and still powerful enough to allow programmers to use the entire HTTP feature set. SSL/TLS support is available as an option.
mod_reserve is an Apache2 module for Linux that extends the Apache HTTP server, allowing it to reserve a certain CPU bandwidth for the provisioning of a service. This module exploits the functionality provided by AQuoSA, whose API is used to reserve CPU bandwidth for execution of tasks. In this way, the module can force the Web server to provide services, like CGI or Perl scripts, using exactly the configured CPU bandwidth. This behaviour is useful in order to provide Quality of Service to certain types of services, or to prevent the kinds of attacks in which a service can starve all the others.