It was the ultimate viral campaign. So the first inclination among the fine folks of fundraising might be to examine Camping's strategy for ideas that can be used in their own efforts.
But it's a mixed bag. First, we're dealing with the Rapture here. No matter how serious or important your mission, it can't compete with the end of the world. Sorry. Then, many (more likely, most) of the people who believed so vehemently in Camping's extreme proclamations are pretty far out there on the fringe and probably wouldn't respond as well to more mundane appeals. Camping wasn't actively seeking donations, and he has religious fanaticism in his corner. So in reality, you can't credit his "strategy" for the reactions to the Judgment Day campaign.