Already set up:
- PayPal
Other:
- Dwolla
- Flattr (does anyone make real money? Is it too easy to be used as an alternative to a substantial donation?)
Social or environment oriented:
- Care2
- Change.org
Crowdfunding - as Appropedia and/or as individual supporter campaigns.
Check P2P donations; ask Nicolás Mendoza (Michel's colleague) for his suggestions.