Pictures of people in costumes from Mardi Gras 2008 are viewable from this video. The previous years are compiled into photo albums that contain individual photos with descriptions that are searchable.
I didn't shoot this video, and I am not particularly fond of the music choice (I would have preferred some good Mardi Gras music!), but the video does have some great shots of people in costumes. This was taken in the French Quarter on Fat Tuesday.