Written and originally posted by OpferOk, here is a mod that allows you to set up an unlimited number of extra form fields to the member center, to the message display (optional), to the registration form (optional) and as a tag for every member (optional).
Below is a screenie of the admin center (it's called "Fields Setup" in the Admin Center):

Ok, time to explain what each column stands for:
1. Field name: I guess that's clear, the name of the information/field
2. Force: When activated, each user has to give this information when registering.
3. Permanent: When activated, only Administrators can change that information, when not activated, the user the information belongs to, can change it.
4. Show: Also clear, when activated, this information is shown in the Message Display, when not activated, only Admins can see this information.
5. Tag: When activated, it will show this information as a tag, like "NH|Opfer".
More screenies of the Member center and the Message Display:


Just upload the mods inside the attached zip file to the mods folder on your server (ASCII).
One is for those with the English language pack installed. The other is for people with the German and English language pack installed.