Wikipedia has a big fundraising push right now. Here’s what I sent to firstname.lastname@example.org:
To whom it may concern,
Wikipedia is a useful resource for uncontroversial areas, but in areas of controversy I find it quite biased. My own extensive biography at Wikipedia is terribly slanted. Colleagues who try to correct misrepresentations find their edits scrupulously removed. Until and unless Wikipedia is more careful about fact-checking and provides some means for correcting the bias of editors, I cannot in good conscience donate to Wikipedia. At the very least, I would suggest that acknowledged experts in an area (such as the living subjects of biographies) be given a 1,000-word response section to relevant articles — sections completely at their discretion and beyond the control of biased editors.