I added an XFire modification to Southperry since it seems to be popular around here. Check out your options menu in the User CP to enable it (User CP --> Edit Your Details --> Scroll to bottom). Your XFire membership status will show below your IGN/Guild information in each post.
In order for your XFire info to be seen, you must:
1. Be a member of Southperry
2. Have input your username into the User CP
3. Have input what kind of background style you'd like
Members of Southperry will only be able to view XFire info of themselves and others if they have filled out their own information in the User CP. Guests will not be able to see the XFire information. So, consider this an exclusive group.