I am the kind of donor who is much more motivated to give by seeing what specific projects are on offer. The reason boils down to the fact that I have slightly different values (namely, hedonistic utilitarianism focused on suffering) than the average of the SIAI decision-makers and so want to impose those values as much as I can.
In case you missed the notice at the SIAI Blog, the Singularity Institute's next Challenge Grant is now running - $100,000 of matching funds for all donations until February 28th, 2010. If you want your donation to be tax-deductible in the U.S. for 2009, donations postmarked by December 31st will be counted for this tax year.