[quote name='odintal']Jurassic Park Trilogy[/quote]
This is, IMO, the best answer in the thread. The LEGO games work best when they're mixed with a well-established franchise with a lot of material to mine. This is why the three franchises already in use worked so well.
If the rumors of Harry Potter Lego games come to fruition then I will be happy as well. Lego Superman or Justice League could work quite well although I feel a Marvel themed Lego game would fall flat.
I can't think of any other franchises I'd like to see rendered in block form. However, now that the Lego games have become a juggernaut on their own I would like to see original adventures based in the Lego brand universes (i.e. City, Castle, Space, but NO Bionicle) and/or the Lego MMO brought to consoles. I'm not looking for much in the way of story here. I just want an easy game I can breeze through mindlessly and rack up the trophies/achievements while I'm at it.