WebObjects provides a comprehensive IDE for developing, deploying, and extending Java server applications. Applications can be deployed on any J2EE server, as well as Apple's optimised server product line.
If you are a Mac OS developer and XML is your area of interest then MDiP have a range of XML products of interest, including XML and CSS editors, and the XPublish XML server.
Ranchero software specialise in software tools for MAC. Their chief offering is NetNewsWire, an easy-to-use RSS news reader for web sites. It presents a familiar three-paned interface like that of Outlook Express or Mailsmith, to display websites and their news. A number of Open Source software items for MAC are also available for download.