A recent suggestion by Jack Horner + crew (and a hot debate on Wikipedia currently) is that Triceratops and Torosaurus are the same species. Now I think that's bogus. But here's the links if you want to see:
http://www.physorg.com/news198306111.html and http://www.earthmagazine.org/earth/article/378-7da-8-4 --- news on the subject (I couldn't find the original paper)
What do you think? Or do we just need more information to tell if this is so?