At Systelligent we develop User Interfaces via Web Apps. It is hard to describe them as just Web sites that may mean different things to different people ranging from static marquee sites to eBay or Amazon style trading portals.
We develop in two different technology stacks.
One, is the Linux, Apache, MySQL, PHP group also called the LAMP stack.
The other is the Windows, IIS, SQL Server, C#, ASP, Dot Net technology group.
In both cases we follow the same agile approach by developing modular components for a framework selected for the intended purpose of the site. This tact allows rapid, cost effective development with greatest value delivered early and enabling incremental development as opportunities arise or along a predefined roadmap.