In the new HD seasons intro, the generic dancers on the stairs are replaced by actual characters from the show.
In the season 5 episode "Stewie Loves Lois," the end credits are rearranged to mimic the end credits of "All In The Family," complete with the show's closing theme song.
Every few seasons, the instrumental version of the title theme that plays over the end credits is replaced with a new arrangement. To date there have been 5 main arrangements of the closing credits theme (this, of course, does not include "one-shot" versions that are relative to a specific episode.)
The end credits of 'Peter Griffin, Husband, Father... Brother?' feature Peter and a posse rapping the lyrics to the show.