I could go on for hours about the value of Wikipedia to every person on this planet. But let me go right to the bottom line: take a few seconds to show your own appreciation for by making a donation. (With PayPal it literally takes 30 seconds.)
Personally, I include Wikipedia among my charitable contributions because no matter what other cause you support, it’s very hard to argue that a better way to share and disburse knowledge in this world isn’t a contribution to that cause as well.
So I consider my Wikipedia donation an “automatic matching contribution” for every other donation I make.