The first thing that always comes to my mind when I think of recreating scenes with T2 are shots from the Lord of the Rings. The Great Tree of Lothlorien would be cool.(The way it originally was described by Tolkien would suit T2 much better, but it's the artist's call obviously)
Another one would be the big stone kings guarding the Anduin river(If somebody did that right, it'd look amazing). There is, of course, Mt. Doom, there are the Gates of Mordor, we have Minas Tirith, the village of Rohan, Helm's Deep, Barad-dur(Sauron's Tower). Ents would rather be a challange to recreate, I would think. It goes on indefinitely...oh yeah, you can't forget the Grey Havens, Isengard, Rivendell, or the Lonely Mountain!(and of course, the Shire)
I'm sure people have already tried doing LOTR with Terragen, but I don't recall seeing anything especially noteworthy.
I can think of a few shots from the "Aliens" movies that might be interesting. Some shots from Indiana Jones might be cool(Particularly the Last Crusade, when they go to Petra)
Star Wars offers limitless possibilities...but I think I've already seen this done.
There are more: The Mummy, Deep Impact, the Abyss, Robinson Crusoe on Mars(on older movie), Independence Day, Pearl Harbor, Jurassic Park, Godzilla...
Myriads upon myriads of ideas...
Unfortunately, I don't know if I'll have the time this season. I'm still considering trying something, though.