In the days since the earthquake in Haiti, Americans have shown their generosity with millions of dollars in donations.  Tonight, President Obama signed a bill into law that makes it easier to give.  This legislation will allow taxpayers to receive the tax benefit from donations made to the Haiti effort in this tax season, rather than having to wait until they file their 2010 tax returns next year.  Specifically, cash donations to charities for the Haitian relief effort given after January 11 and before March 1 of this year may …