This blog post from 2011 mentions a few organisations that accept donations to run Tor exit nodes. What all organisations are there that accept donations to run exit nodes on my behalf?
There's actually been an explosion of non-profits lately that are organized for running exit relays. In rough order of appearance on the scene:
Zwiebelfreunde, aka torservers.net, is the original organization formed for this purpose, and they still operate the most capacity in the Tor network (Germany).
The Swiss Privacy Foundation has been running Tor exits for many years now (Switzerland).
NoiseTor is a project of the San Francisco-based Noisebridge 501c3 non-profit (USA).
Föreningen för Digitala Fri- och Rättigheter (DFRI) is a Swedish non-profit that runs several large exit relays (Sweden).
Frënn vun der Ënn runs some large exits as well (Luxembourg).
Nos Oignons is a French non-profit started by Lunar et al to run fast exits (France).
Hart Voor Internetvrijheid is just starting up, organized by some of our friends in and around Amsterdam (Netherlands).
In addition, organizations like the German Chaos Computer Club have run fast reliable exits for many years, and would welcome donations and help.
Keep an eye on Zwiebelfreunde's partners list for new ones.