Did a severe ID error last time when I said this was a spotted house gecko. Thanks for budak, juan and tidechaser for correcting me. Also Daniel who went one step further to help me email Dr leong tzi ming, our local herpatofauna expert for the species.
This is a Common gliding lizard, Draco sumatranus. As described by him, "It is fairly common around parks & forest edges in Singapore and Southeast Asia. This genus (Draco) has many species though, and most of them only live in good, pristine forest. When you see it 'flying', it is actually gliding, and the sight is quite unforgettable." More on ecology asia.