There were six previews (as best as i can recall) before the movie, four of which were very interesting. The first one (i think) was for the new Tron movie, which certainly looks very cool. I hope the actual movie comes out as well as the trailer. There was a trailer for "the Green Hornet," which i hadn't heard was being made into a movie. It looked like it might be cool. There was a trailer for "Cowboys & Aliens," a movie i also hadn't heard anything about before seeing the trailer. Looks like it could be awesome or it could be terrible. The final good trailer was for "Green Lantern," which i had actually heard was being made into a movie. That's certainly a super-hero movie that i'm conceptually interested in but the trailer didn't do a great job of selling it. Finally (in terms of interest if not order) there were trailers for the next Kung-Fu Panda movie and one for a Yogi Bear movie. The Kung-Fu Panda one was really short and gave no idea about what the actual concept of the movie was, and to me at least it seems like one of those cases where the first movie didn't leave a lot of room for further development. The Yogi Bear movie just looked dumb, but i never enjoyed the original cartoon so i may just be anti-biased.
Edit: Oh yeah, i forgot, there was also one for "Dawn Treader," which looked pretty cool and definitely falls into the larger "interesting" set of trailers.