As the name implies, web applications are more than web sites, they are applications that run over the internet. Much like a web site or build on top of a site, a web application gives you greater ability to meet your customer's needs from your site by adding additional functionality and features.
We divide web applications into two basic categories: Data Entry and Automation.
Data Entry Applications are pages where a visitor enters their information and it is moved to a database for review or further processing. Automated Applications are the process components that run subsequently from the data entered. For example, a site that takes client applications would run an automation application to pull credit or pass to a loan officer when the application is complete. Processing begins when the data entry segment is complete.
There is a great deal of opportunity in the service industries for not only data entry applications, 
but automation as well. Equipment service companies can benefit greatly with applications that employ a little of both technologies. We are in the process of creating sites that take data entered over a secure socket or mobile device from an employee and then generate reports that are delivered to their client by email or left for them when they login.
Having the data in a SQL Server database we can further process queries for management in the form of business indicators.
There is no end to the possibilities for building your application out in an online format. Start automating routine processes and you will secure a level of functionality years ahead of your competition.