Graphviz is open source software for graph visualization, representing structural information as diagrams of abstract graphs and networks. The package includes web and interactive graphical interfaces, and auxiliary tools, libraries, and language bindings.
Hackety Hack will teach you the absolute basics of programming from the ground up. No previous programming experience is needed! With Hackety Hack, you'll learn the Ruby programming language. Ruby is used for all kinds of programs, including desktop applications and websites.
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Originally developed for text manipulation, it is now used for a wide range of tasks including graphics programming, system administration, network programming, applications that require database access and CGI programming on the Web.
PostgreSQL is a powerful, open source object-relational database system running on all major platforms. Support for native programming interfaces for C/C++, Java, .Net, Perl, Python, Ruby, Tcl and ODBC among others.
Solr is an open source enterprise search platform from the Apache Lucene project. It operates as a standalone full-text search server within an appropriate servlet container, such as Tomcat. Solr uses the Lucene Java search library at its core for full-text indexing and search, and has REST-like HTTP/XML and JSON APIs that make it easy to use from virtually any programming language.