Hey, it's pretty simple: TANSTAAFL -- There Ain't No Such Thing As A Free Lunch!
Every time you click a link, it costs the Wikimedia Foundation a tiny bit of real Cash Money. When you see Search turned off, or pages loading slow -- that's called running short of cash. Wikipedia is growing very quickly, and like any growing child, needs plenty of food -- servers, connections, and human labor to keep the whole project infrastructure running.
Yes, it's all free-speech-free -- but none of it is free beer!
Do you have a job where you are paid money? What is your time worth? How many hours have you spent here today? Surely, you can reach into your pocket and donate a trifle to keep the project afloat.
One dollar. That's what you need to kick in today. One dollar, one euro, one of whatever local money you use everyday -- the price of a bottle of Coke. You drink the Coke in five minutes and forget it forever -- or you help to support Wikipedia for centuries to come.