I've LOVE the Philippines, and I fly from Atlanta as often as I can, and I stay for as long as I can.
All I have ever needed is my passport and a departing ticket. The passport allows you to stay for 21 days For an extension of up to 59 days (counting the first 21), you can pay required fees and submit paperwork to any Philippine Consulate in the US before you go, or you can work through Immigrations in the Philippines after you get there. I've been told some travel agencies there can help with the extension also.
In June and July of 2005, I overstayed the 21 days. I told the Immigrations officer upon arrival I was going to do this, and I show him my departure tickets. He told me I could simply pay the fine which did not amount to much. That is what I did.
You can extend for an additional 59 days through Immigrations. You can do this indefinitely, but you must leave the country once a year. You can go to a neighboring country for a day, and come back to repeat the process for another 59 days...for one year... get it?
You can get more information like this through the Yahoo Groups called "Living and Retiring in the Philippines." Your question is asked there frequently.