Park Road Web Development specialises in the open source content management system, Drupal.
Drupal is built on a solid and secure core which is robust, flexible, extensible and secure. It's open source, so you're not going to get locked into any proprietary system, and because of it's popularity and large user community, there is good documentation, great forum support and a large pool of Drupal developers. It is under constant development so you are sure to not get left behind when technologies advance. Drupal was also the overall winner of Packt Publishing's 2007 Open Source CMS Award http://drupal.org/node/188772 and now the 2008 award too: http://drupal.org/Drupal-Wins-
Today, Drupal powers many high profile sites, including the homepages of Warner Brothers Records, The New York Observer, Human Right's Watch, Fast Company, Popular Science, and Amnesty International and project sites by SonyBMG, Forbes, Harvard University, and more. Drupal can be used to create personal weblogs (Tim Berners-Lee), deliver podcasts (TWIT.tv), connect online communities (SpreadFireFox.com), form artist collectives (Terminus 1525) or inform the masses (The Onion).
For an example of more Drupal sites, see the listing here.
Using an existing CMS means you don't have to rebuild the wheel when it comes to the basic functionality like logging in, security, creating and editing content. All these are in place, and if they don't exactly meet the requirements, they can be extended in a way that enables one to build on the existing code.
You also don't pay for the software itself, just the installation, configuration and customisation, and because it's open-source, there are also no licenses, and you own your site data (some companies don't allow you to take your site data with you if you part ways with them).
Drupal does have minimum hosting requirements, such as PHP and a MySQL database. See the Drupal site for detailed system requirements.