I loved Invader Zim. And unfortunatly, emo kids kind of took over the show and thus affected the merchandise that has come out lately.
GIR is adorable.
But they will never do a live action. Part of the reason the show is good is the style of the animation. You can not recreate that in live action. Also the original guy, Jhonen Vasquez, that created the show is not going to come back. When Nick cancled the show in lew of more "Rugrats-style" programing he had a falling out with the network.
And Nick is never going to sell the rights to the show to anyone else. Nick lost alot of money years ago when they sold failing show "Doug" to Disney (who revampt the show and it became a sucess again). So, Nick would rather beat the show to death in reruns then do anything else with it.
Like I said I loved the show. The animation was well done and had some very interesting humor. But it makes me sad to see emo kids embrace it so much. Not to say that all fans of the show are emo (I am not), but I would say the majority are.