Air Serv Intl called me in 1993 for a background check on a pilot. He got hired with them, and flew in Africa for one year. I met him later, and this is what he told me about their operation:
"Air Serv Intl. is a humanitarian non-profit organization that prefers pilots that would like to make our world a better place. They want people not only motivated by money. They are not the best paying humanitarian operator in the "business". Other commercial humanitarian operators pay better. Air Serv Intl are, however, still one of the most serious humanitarian operator, with good maintenance, health insurance and so on. (Non-profit unlike several other commercial humanitarian operators)."
My friend flew in Kenya, Africa, where they had Twin Otters, KingAirs and Caravans. Co-pilot pay was 1400 USD @ month and Capt 2000 + food & housing. I also know another pilot who flew with Air Serv Intl. for several years. He said nice things about them. (He is now with SoutWest).
I got a good feeling for their chief pilot when he called me.
Just heard that they are setting up a humanitarian operation to help out, once the people of Iraq are liberated. Search and find their website to confirm this and other details.