Have a look at the forum source (this one for
thebutterzone's profile)
<img src="http://status.icq.com/online.gif?img=5&icq=235892812" alt="235892812" width="18" height="18" border="0" />
When an ICQ account is added to a user profile, the forum adds an image with user information, which is inserted below the avatar area in every post a user makes. This allows a third-party to track IP addresses every time a post by a user is viewed, and to know the ICQ number of the user who's post was viewed.
