Console Wallpaper (I think)
 

I have seen a Linux Box running a picture behind the console. Each console had a different picture. The console text was in front of the picture. Any idea how to do this? Which file to edit, or package/module to download? Thank you in advance for your help.

Using Konsole, you can set a background image for the terminal. Click Settings - Configure Konsole, and select the Schema tab.

I think (from memory) that eterm will give you a random background image for each terminal window.

--Ian

Not in Konsole
 

The system I saw had a background, outside of the X Window Manager. Each terminal (tty1, 2, 3, etc..) had a different wallpaper, as soon as he logged into the terminal he was at. Any ideas.

There are a few different ways to do this. Bootsplash, Gensplash, Splashy (does this?), depending on your distro a one or more may be specifically easy to set up.

Almost there
 

I am using Slackware 10.2 kernel 2.6.15.2(well... trying to use). What file do I need to edit in order to add this background after installing Bootsplash or whichever? Thank you

Check the instructions :D

Basicly you make a initrd image with the image and it's configuration file in it.
Here's a link to Gentoo how-to about this. It's easy enough to adapt to Slack
http://gentoo-wiki.com/HOWTO_gensplash