Get out your grant-writing pen! According to the AAFRC Trust for Philanthropy's annual report, Giving USA 1999, foundations led the way last year in charitable giving. Reason: As the stock market surged, so did the assets of non-corporate foundations. Since private foundations are required by law to pay out about 5 percent of their assets in grants, the public good was benefited to the tune of $17.09 billion. Still, some recipients fared better than others. Arts, culture, and humanities organizations actually experienced a slight drop in donations last year (down 0.8 percent, to $10.53 billion), while giving to causes benefiting environment/wildlife (up 28.3 percent, to $5.25 billion) and public/society (up 29.5%, to $10.8 billion) soared. Other big getters were health and human service organizations, each racking up $16.89 billion (+20.4 percent) and $16.08 billion (+27 percent), respectively.