We had a brief discussion on the G+ Internal Martial Arts forum about a great video of force training at the Wudang mountain by Wudang Pai, an excellent kung fu school preserving and teaching arts practiced by Daoist sages at the Wudang Temple.
Baguazhang, demonstrated here by Grandmaster Wong Kiew Kit, is often considered an internal style of kung fu. Image taken from http://www.shaolin.org
Someone asked the very good question of what kung fu system would be best for them. Naturally, this is informed by many factors such as what you want to get out of kung fu, what you are willing to put up with, if a master is willing and able to teach you, etc. Here is what I replied with:
Xingyi Quan is considered one of the three Chinese internal martial arts according to the classification wrought by Sun Lu Tang. Whereas Baguazhang and Taijiquan are often characterized by circular motions and open palms, Xingyi Quan is seen as a far more linear, closed-fisted, and aggressive art.