I think the Methuselah Foundation's credit card idea might also be a good way to receive donations without people actively donating money. Probably also buys more warm fuzzies per dollar, since you can feel good every time you use your credit card.
Those confident in their willpower can get a credit card with 2% cash back rebate and just commit to donating the rebate. Methuselah Foundation's card only gives a 1% donation.
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.