I think it would be a good idea to display the IP number and/or the name of the computer from which a user is posting. I think it would solve the forum's 'multiple identity' problem. Or at least rip the problem's mask off. What I have in mind would look something like this:
If this is an option in the forum's software that can be enabled, I would urge you to do so.
There have been a few heated debates in the past that could have been completely avoided if this simple yet powerful piece of information were publicly revealed. It would stop most false identities. You couldn't post under two different identities in the same session and claim that the separate identities are actually separate people and get away with it. Sure, there are ways to get around this if you are hell bent on owning a false identity, but for most it is impractical.
The only trump to this that I see is privacy and security. As for me, I could care less if anyone knows who I am or where I live or what computer(s) I use. But I could see someone not wanting to contribute privileged information to the forum for the fear that their identity might be traced or that they may face retribution for something they post. Then again, if it were that sensitive, the forum could be urged to reveal the ip of the poster anyway. Another valid concern is if someone feared harassment that could be brought on by their ip becoming public, like if I had been claiming all along to live in New York City for privacy reasons and then it would suddenly become known that since most of my posts are from uiowa, I am from Iowa City. Or if someone claimed to work for one company, but all their posts come from another company's domain. Especially if it were from a long time and highly respected user. Maybe some would just not want everyone to know where they work (if that is where they are posting from).
In general though, the internet is not a private and secure place. If you send someone an e-mail, even with a bogus hotmail or yahoo mail account, YOUR ip is still stuck in the full headers of the message. It's very hard for the layperson to remain anonymous. If you visit web pages, your ip is tracked. That's just the way things are.
Perhaps each user could choose whether or not their ip is revealed. Make it an option in the user profile? Or perhaps if you had a special reason for not wanting to reveal your IP(s) you could ask the administrators to not show it? Or better yet, not show the IP depending on what/where it is, like "Don't show my ip if it is from the domain abc123.com because that when I'm at work but all other times I don't care." It's hard for me to say because I don't know what is and isn't possible.
In the end I think that everyone's IP should be revealed with exceptions made in special cases where the user could convince the administrator that they have a good reason for keeping their ip private.
P.S. And of course I'm interested in what other users think as well.