I have seen some users show a picture of their network profile on the profile tab. How can I add this for my own account?
Go to your Edit Profile & Settings -> Flair
Under the "How do I use it?" section, copy the HTML code which is in the "Normal flair" or "Combined flair" section.
Paste the HTML content in the Edit Profile -> "About me" section.
Now, go to your Network profile and click the "Update profile Info" link, in the model dialog window, select the Stack Overflow site in the "Choose a site to copy profile information from:" drop down list.
Now you can see your combined flair in the Network Profile.