Apache is a free and open-source cross-platform web server software.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Drupal Multisite enables separate, independent sites to be served from a single codebase.
Drupal is a free and open-source web content management framework.
OpenLayers is an open-source JavaScript library for displaying map data in web browser.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.