You might want to take a look at !
Greater Good. I have heard good things about them. You will have to register with them and then you supports will have to select you as their choice for donation.
There is also an extensive list of
NP Fundraising Resources here.
You should also look at
CafePress which would allow you to sale, with no upfront cost, products with your brand and message on them. It's free (basic store) and any nonprofit that does not do this is simply nuts