By default, a SharePoint 2007 (MOSS) My Site page does not contain a link back to the portal it serves. This leaves users confused about how to get back to the main portal other than using the Back button in their browsers.
There is a simple fix for this. From the My Site page, choose Site Actions/Site Settings. Under Site Collection Administration click on Portal Site Connection. Click on the radio button next to Connect to portal site and enter the URL and name for the portal site. (Example: http://server/portal/ and Portal Name). Click OK to save. (See this link at Microsoft Support for how to accomplish this programmatically.)
Now, every user will see the portal name (in the example above, Portal Name) in the breadcrumbs on the top left of the My Site page. Problem solved.