As a My Site site collection administrator – here is how you would add a link to everyone’s My Site top nav bar:
1. Go to Central Administration on your farm.
2. Under Application Management click Manage Service Applications
3. Click on User Profile Service Application
4. Under My Site Settings click on Configure Personalization Site
5. Add new link with the bewlo UI.
Also, as mentioned – you can let your users add their own personal links to their My Content site. Here is how:
1. From My Content site, user clicks Site Actions-> Site Settings
2. User clicks on Top Link Bar and adds or removes links as they see fit.