InfoPath

Bold endeavor HTML forms are commonly cited as one of the more decrepit pieces of the Web, and Microsoft set out to create a stronger tool for both intranet webs and SOAP-based web services.
Reinventing XForms Microsoft has fairly consistently denied any competition between InfoPath and the W3C's XForms work in progress, but both are definitely working on the same problem set with some different approaches and features.
GUI for Web Services InfoPath seems most compelling in a Web Services context, where it offers the change to put a human interface on what is more commonly sold as program-to-program communications.
Proprietary built on Common The guts of InfoPath are familiar JavaScript, XML, XSLT, and CSS, but they're extended and integrated with a new set of tools that isn't publicly available or specified cooperatively.