I wanted to build a report that would show our donations year-to-date and compare that to the same time period for last year as well as previous years. I couldn't find a simple way to do it, but I did find a workaround.
I created a new formula field on the donation object in SalesForce called Month and Day of Donation. Here is the formula:
It's a little odd. It basically creates a new date in the current year with the same month and day from the donation. So now I can use this filter criterion in my reports:
Month and day of Donation less or equal TODAY
And it will show only donations for the time period of Jan 1 through today for each year. It works, but there might be a more elegant way to do this. If so, please let me know.