For everyone proudly displaying their old ICQ numbers, just be aware that there are still sites that have some of the info tied to the numbers archived (presumably what was made public/status). So, there may be some easily-access publicly identifiable information that you don't want associated with your current HN username.
(I just did a search and I found that my old icq# had a phone number linked to it)
ICQ counterpart in Poland at some point started using gg: pseudoprotocol and that allowed more aware people to track others activity across the web as most of us included their UINs in post footers on forums
