According to Amazon Japan, two short OVA of Hakuouki were announced to be distributed to those who purchased all the six volumes of the DVD. A fandisc game "Hakuoki Zuisouroku (official website)" and an official parody "Hakuoki SSL (a high school parody)" will be animated as about 10 min long movie.
Nikkan Sports reported a stage play of Hakuoki. Saotome Taichi (official blog) will play Hijikata. The play will be shown this October.