I had a chance to experience Busch Gardens Tampa's Howl O Scream last week, and it's a hoot. There are six Hauned Houses and an upcharge 7th one, called Alone, that is well worth the extra price ($40 for a group of four). We saw numerous hordes/gangs of scareactors roaming the streets and menacing other visitors.
Here are the two shows from the event, in full:
Midnight Hour:
http://www.youtube.com/watch?v=kKRQLb4mJJs
Fiends:
http://www.youtube.com/watch?v=8s5x5H3PMH8
Then, part of this Disney-focused slideshow video will also show more of Howl o Scream.
Slideshow:
http://www.youtube.com/watch?v=K8S5eO_vCBk
Enjoy!