Here is a good list of online donation processors: http://www.affinityresources.com/pgs/awz55Online2.shtml
Some of the entries are a bit out of date, as the list is only updated annually. Most entries are correct, though. Note that there is a 2nd page with additional information.
(Thanks, Robert Weiner!)
Addendum: There is also a useful comparison chart of online registration ASPs on the Consultant Commons at http://www.consultantcommons.org/node/37
Compilations of applications and resources on donation management and fundraising tools can be found at these two useful sites:
Tom Fraise also has a comparison matrix downloadable from his site, allowing you to compare applications according to a number of criteria.
Gunner and the Aspiration team have been an incredible inspiration and resource for us at OpenNews. From facilitating at events like MozFest, we learned about inclusive, engaging, collaborative event design that has shaped our own event SRCCON and influenced the community we serve in journalism.
