tiger airways is a singapore-based airline and is not permitted to fly domestic routes within thailand. it does, however, fly from singapore to various thai cities including bangkok, krabi and udon thani.
one excellent airline not mentioned is bangkok airways. it's not actually a low-cost airline, but specialises in routes not served by others, such as samui-bangkok or samui-hkg (perhaps equivalent to the uk airline flybe.com). the female cabin crew are among the most attractive of any airline.
ian.