Thought this was going to be another thread about no one using instant messaging anymore. There's a form in your profile to fill out if you want it public (you've filled in the ICQ one). Icons are at the top right of each post.
Members who use it can enter the details in the contact info in the user profile.
The following entries are possible:
ICQ UIN
AIM Screen Name
Yahoo! ID
MSN ID
Skype Name