Let's see, favorite openings huh? I'm going to have to go with the second Bleach opening, all the D.Gray-Man openings, Initial D's Project D opening, and Shuffle's opening. I also can't forget the Lucky Star opening and the Darker Than Black opening.
Closings now. I'd say the Bleach closings because they're pretty funny. Other than that I usually forward through the closings to the next episode.