Airlines, struggling with soaring fuel costs, are changing the terms of and adding fees to their frequent-flier programs in an effort to find new revenue streams. For example, US Airways will eliminate its bonus miles and implement a processing fee on redemptions starting Aug. 6. "These programs are supposed to be free," said Jay Sorensen, an airline industry consultant. "What we're seeing is the degradation of the entire product. Frequent-flier programs are as challenged as the rest of the airline product."