[mertd]

Once or twice a year, I go to http://www.charitynavigator.org/ to do my own research and donate to a charity that I think will make good use of the money.

Lump sum method has two advantages:

1) Easier to keep track of for tax filing.

2) Your employer might have a donation match program. Again it is easier to file a form and tell them to make a matching donation.