When members of the U.S. Senate finally head home this week, they will be leaving the future of 50 individual and business tax breaks in limbo. All expire at the end of 2009. Among the disappearing breaks are the research tax credit and an annual alternative minimum tax "patch," which keeps 23 million additional middle-income Americans from being forced into calculating and paying the dreaded AMT. (For 2009, with the patch in place, 4 million upper-middle- and high-income families will pay AMT.)