Normally, I'm not a huge fan of Wikipedia for genealogy - there isn't enough detail on the towns I study - but I have to admit, it can come in handy in unexpected ways. I've mentioned a few times that I'm currently studying one particular ancestor. She's proven quite hard to trace. We have no idea when she immigrated or where she was buried.
I've almost gotten one of those problems solved - thanks to Wikipedia. Her death certificate lists where she's buried, but the only cemetery of that name was founded four years after her death. I would have given up, but I happened to notice something in the article. The cemetery was called the "new" cemetery. The old one had been moved... and the article told where.
Lesson learned. Next time I can't find a cemetery, I'm checking Wikipedia. I may find nothing. But I may find gold.