I've gotten a lot of questions around Line of Business solutions that would allow our customers to fill out forms on mobile devices to collect data. While you could create a website, develop a form and connect it to a webservice that would collect the data Microsoft has a solution to do exactly that: InfoPath.
Similar in functionality to how InfoPath Forms Services renders browser-enabled form templates in a typical desktop Web browser, InfoPath Forms Services also renders forms in browsers on handheld, or mobile, devices. Most mobile devices are supported, including PDAs (Personal Digital Assistants), smart phones, and any device that supports a Web browser with HTML, cHTML and xHTML; WAP is not supported. There are, however, some key differences in how forms are rendered in a mobile browser and considerations to keep in mind when designing a form template for use on a mobile device.
With Microsoft Office InfoPath 2007 and access to a server running InfoPath Forms Services, you can create and deploy InfoPath form templates that can be filled out on a mobile device. For an overview of mobile form templates, see Designing Form Templates For Use On A Mobile Device. Its as easy as creating a basic InfoPath form template for use on a mobile device and then testing and debugging it by using downloadable tools that are also available with Visual Studio 2005.
Designing InfoPath 2007 Forms for Mobile Web Browsers
How to: Create, Test, and Debug Mobile Form Templates
Integrating InfoPath 2007 Forms in Web Sites Using Visual Studio
In addition to the built in solution available via InfoPath 2007 there is also a compelling solution from a Microsoft Partner: Formotus (www.formotus.com)
The main advantage from Formotus is the ability to put a client on the device that can handle offline scenarios.