Or-Yah Maor 
Teaches Hatha yoga, prenatal and postnatal yoga in Bangkok.
http://www.or-yah.com/Pieter 
Conduct classes in Kundalini Yoga as taught by Yogi Bhajan in Banghok.
http://kundalini-matashakti.com/
Yoga Elements: Bangkok 
Teaches Vinyasa and Ashtanga methods of Yoga. Features schedule and location.
http://yogaelements.com/
Hatha Yoga: Thailand 
Offer 10-days workshop for beginners and classes for intermediate and advanced practitioners in Mae Sariang, Northern Thailand.
http://www.geocities.com/yogainthailand/