Python

The Python programming language is actively used by many people, both in industry and academia for a wide variety of purposes. This object-orientated language is quite similar to Java and ASP.NET I found in its ability to create dynamic web pages and various types of software applications. Python integrates well with many other technologies. Apart from Ruby, Python is said to be the fastest growing open-source languages available, used in everything.

A clean object-orientated design and extensive support libraries make Python far more productive than languages such as C++, Visual Basic and Perl. Some of its major advantages include:

Cross Platform - Python is compatible with most major operating systems

Speed - Python is much faster than other interpreted languages.

Extensible - Python makes it easy to write your own extensions in C or C++.

Highly Scalable - The extensibility, speed and power of Python provides access a dynamic set of tools that help you effortlessly scale to larger projects.

Easy to Maintain - Python's natural elegance produces code that is not only easy to read, but simple to redesign and modify as well.

Open-source - Starting as an open-source project, Python's efficiency can be attributed to the contributions of thousands of developers around the world.
I have created a list from numerous sources just listing the possibilities of using python within web documents.
OpenERP, an open source comprehensive suite of business applications
ERP5, a powerful open source ERP / CRM used in Aerospace, Apparel, Banking and for e-government
GNU Mailman, one of the more popular packages for running email mailing lists
MoinMoin, a popular wiki engine
MootiroForm, an open source form creating software
Planet, a feed aggregator
Plone, a user-friendly and powerful open source content management system
Roundup, a bug tracking system
ViewVC, a web-based interface for browsing CVS and SVN repositories
Trac, web-based bug/issue tracking database, wiki, and version control front-end
Python Shell, A Python shell inside the Google Chrome browser.
Turntable.fm, a social media site for interactively sharing music, currently in beta