SAG development created a demo of customized MWS, but I don’t believe it was ever released for general consumption.
If you want to take a quick and easy look at the type of things you can do, log onto MWS as sysadmin rather than Administrator. This will put you into the Portal administration.
Click on My Folders. When the page opens, look to the right for the arrow within a circle (the one on the same line as My Folders). Click on the arrow and select New -> Page. Give a name to the page. Once the page shows in your My Folders page, click on the arrow within a circle on the same line as your page name. Select Edit Page.
This will open the Portal page editor. Down in the lower left, you will see a list of Available Portlets. If you click on Portlets, then scroll down to My webMethods, you’ll see some of the portlets you could pop into your custom page. If you find one you like, drag it into the page inside one of the boxes (such as the Auto-Positioned Portlet box).
Then save your page. You can click on the arrow within a circle for the page again and affect the permissions (perhaps adding an operator to have the rights to use this page.)
That was a quick and dirty demo - just the tip of a very large iceberg.
Another tip to the iceberg you could explore is building your own web app or even your own portlets in the Designer (using the My webMethods or webMethods UI Developer perspectives.)