I had a multivariable calculus class with Dr Zeilberger and he was one of the best math professors or teachers I've ever had the privilege of being a student of. More than other teachers, I got the feeling that he genuinely cared about everyone succeeding: he ran multiple early morning study sessions several times a week, and didn't slouch this duty off to his TAs but was there himself, from 7am until the lectures started at 10. Not to say that my other teachers didn't also care, but he really put the time in to show it. I was always impressed because this was just a sophomore undergrad class, and I'm sure he had "more important" things to do.
His "Opinion 37: Guess What? Programming is Even More Fun Than Proving, and, More Importantly It Gives As Much, If Not More, Insight and Understanding" is also very interesting:
http://www.math.rutgers.edu/~zeilberg/Opinion37.html
Fun fact: Doron is known for crediting his computer "Shalosh B. Ekhad" as a co-author.
I found the responses linked in the article interesting as well: