I like the nonexistant charectar Louie. In season 2, they were planning on killing off Dib and replacing him with Dib's new rival, Louie. But they didnt get a chance too.Thats what you know when listen to the commentaries too much. Narf.
But I still love you Dib.
Other things I know from listening too the commentaries:
Zim is ampadexterous.
Zeta is based on an actual person named Zeta, who had purple hair at the time.
Louie Stuff. All sorts of things about nonexistant Louie.
In the episode Voting of the Doom, Nickelodeon wanted to change the show's name to:
Invader Zim and Dib. Would look like this:

Narf.
Haha. LOUIE ROCKS!