Médecins Sans Frontières (MSF) -- sending doctors where they're needed
The Planetary Society -- promoting space exploration and education
American Indian Science and Engineering Society -- increasing representation of indigenous people in STEM
UN Refugee Agency -- helping refugees (especially from Syria)
Amnesty International -- supporting human rights around the world
Lambda Legal -- supporting civil rights for the LGBT community in the US
Feel free to let me know if you do donate (anonymously if you like)!