The theme for the Dies Irae is one of the most often quoted melodies in music history. I am unaware as to how many composers did this before the Symphony Fantastique but I find it interesting that since the monumental work has become such standard repetoire for orchestras, that melody creeps in all kinds of different places.
Lets take a look (and listen to) at "The Witch's Sabbath"
The Dies Irae starts at about 3:23, pretty catchy stuff if you ask me.
Now lets listen to Stephen Sondheim talk about his musical Sweeny Todd Listen to the narration at about 1:30 to hear what I am referencing. Also, stick around on the video to hear Sondheim talk about "Sweeny's love of death" because it is pretty compelling stuff.
So we can hear that in many ways we are still living with innovations of the Romantic era and especially Berlioz. For that matter we are still living in the shadow of Gregorian Chant, especially when we think of the sheer number of church hymns we have all sung based on chant... I hate cliches, but; the more things change... (well, you know the rest).