Trungpa Rinpoche is credited with being the first Tibetan Lama to work with calligraphy in this spontaneous style. Examples of his work are relatively hard to come by but some examples can be found on the internet.
Trungpa Rinpoche worked with both Tibetan and English script, as you can see here:
The second is from the weblink above, and is from Trungpa Rinpoche's Elegance series - titled 'Elegance overcomes aggression'. His works are in the stewardship of the Shambhala organisation, but alas he passed away in 1987. His direct line of work did not end however, and is continued through the Sakyong.
Tai Situ Rinpoche also known to work with calligraphy and can be seen in the above clip, but the pool of artists working in this way within Buddhist Vajrayana is limited at present, and the art form in this context is in its infancy..
I myself have never even attempted to create a calligraphy. However it is still possible even for an ignoramus like me to be appreciate the variety of approaches that can be seen in this clip. Even in the brief video here one can see themes reflected in the work of Ngak'chang Rinpoche and his students. I am particularly fascinated by the different effects that can be created, the different brushes, and even something so simple as seeing the different ways of holding the brush. Next Friday Ngak'chang Rinpoche will be talking about some of these different approaches, stylistics, and in particular his own approach. There will be ample opportunity to ask about the how- and why- of brush type, choice of ink, brush loading, the choice of paper, as well as the meaning of the calligraphies themselves, the ink spots and the seals and signatures that each work bears.
I look forward to seeing you there!