I was building a SharePoint wiki that utilizes custom security on each page depending on who the user is. To programmatically assign the permissions, I leveraged custom columns on the pages to identify what permissions to set. The problem is, whenever you create custom columns in a wiki, those columns show up on all the pages and you can't disable it through the UI. See below:

It's really easy to remove these columns from showing on the pages. Start by editing the wkpstd.aspx page under DocumentTemplates:

Find the PlaceHolderMain content place holder, and therein, delete the table containing the ListFieldIterator control:

That's it!

Phil

<update 1/6/09>

I got some good feedback from a few individuals on a few more options to removing the columns. Ray Gaida mentioned you can override a CSS style to remove it. Just drop a content editor web part on the page with the following style in it:

<style>
.ms-formbody{
display:none;
}
</style>

Also, Keith Dahlby mentioned a programmatic way to hide the columns by changing the ShowInDisplayForm field property to false. Read more here.