Ko Bu Bu is a round slither of sand approximately 3 to 4 nautical miles from the eastern coast of Ko Lanta Yai. It is a Robinson Crusoe island with thick vegetation in the middle, some 10-20 bungalows with restaurant and bar, sugar-fine sand, helpful locals, and foreign visitors that can be counted on the fingers of two hands (and that is at the peak of the season). It's the sort of "get-away-from-it-all-and-lie-in-a-hammock" type of concept.
Waters around the island are crystal-clear, with good opportunities for snorkelling. The few local workers are friendly, helpful, and discreet, and the bungalows have been constructed and decorated by someone with a very artistic eye and mind.
I have to admit that as my visit was pre-tsunami, I am not sure of the state of this place at the moment, which must have been overpowered by the waves.
Perhaps, because of its small size and flat surface, the water came and went with less damage than elsewhere.
The cost of the bungalows was only few 100 Bhats per night, and food was very inexpensive and fresh, but on the minus side is the fact that you are "trapped" on the island until the next boat comes. This can be both a "minus" and a "plus", however.