I contribute from time to time. I generally focus my contributions on my interests (water law and policy), food allergies (seeing that many articles fail to mention allergies despite their seriousness and prevalence), and where I have lived in the past (e.g. Los Angeles).
I'm also a bit dismayed by Wikimedia's push to collect money is apparently doesn't need, or at least it doesn't need in the way framed by ads begging for money. See [| Wikipedia has a ton of money. So why is it begging you to donate yours?]