Who's the airline who offers such cheap rates? Meet Cebu Pacific Air.
We have flown with this airline a number of times. Their service is nothing to boast about but you can't ask for too much for such a price. They always, as in ALWAYS, have way discounted airfares. All you need to do is to visit their website often for the weekly updates of discounted fare and you need to plan ahead since earlier you book, the better chance you can get the cheapest rate.
Here's a rundown of flights we've flown with Cebu Pacific, the month/year and the price of ticket per person:
MNL->HKG - August 2009 - 60usd
MNL->SIG - August 2010 - 80usd
MNL->KIX - September 2010 - 180usd
MNL->ICN - May 2011 - 110usd
Note that all those flights are round-trip fare. It's mad cheap compared to domestic flights here in the US. You can also book a full vacation package from their website including hotel accommodation, airport transfers and daily tours.
So if you have an upcoming vacation or a business trip to the Philippines, consider checking out their website. Might as well see more of Asia if you have the time and a couple of hundred bucks to spare.