I wanted to get rid of the My Site and My Links navigation elements at the top of the SharePoint sites.
1. Log into Central Administration.
2. Find Shared Services Administration and select the web site under that which you want to turn off My Sites for.
3. In the “User Profiles and My Sites” group, click on the “Personalization services permissions” link.
4. To remove the functionality for most of your users, select NT AUTHORITY\Authenticated Users.
5. Click “Modify Permissions: Shared Service Rights” from the top menu.
6. Uncheck “Use personal features”. Click OK to save.
You’ll need to close and open your browser to see the changes.
Thanks to: http://stevepietrek.com/2007/12/11/disable-mysite-and-mylinks-in-moss-2007/