For US citizens, it may be worth noting that if you give before the end of 2013 (within the next 10 days or so), you get to count it as a tax-deductible charitable contribution for this year, which will mean a larger refund from the IRS next year after tax day. You only get to do this for up to half your income for each year, so this represents an opportunity cost. (I don't know about other countries' tax laws--in fact, I don't know much about US tax laws either, really, so don't cite me as an expert.)