I have numerous accounts on web applications, forums and other related things. I ended up entering numerous time the same information about myself: name, handle, e-mail, icq number etc. I really wish that forum engines would integrate a mechanism where I could give a link to a special file (vcard could probably do the trick) and the relevant information would be retrieved or better yet, linked against this file. Ideally, my first forum (or simply my blog application) could be used as a master, with a nice interface to edit the information.

Such a system could be reasonably easy to implement, and would ensure that more and better information is contained in the contact information of forums. Some care should be taken to avoid that this becomes yet another tool for spammers, but this could be handled by using a simple password authentification scheme, basically, when registering with forum X you would give it a url/password pair, the url would contain personal information and the mail address to use to send the mail with the confirmation link.