I'm proud to say that my Half Baked Idea:
http://www.halfbakery.com/idea/Cleaning_20the_20homeless for Cleaning the Homeless: "Offer secure, private, single person showers at low or no cost." has made it to the second page on the list of all time best ideas at the Half Bakery. It's one of the few somewhat political ideas that have been allowed to stay on the site (the owner doesn't allow politics). Other best ideas on the site from other authors include "Preformed Cream Cheese Rings for Bagels " and a "Tumbleweed Dispenser: For when idiots talk" so you can see that it's one of the few "best" ideas that isn't sort of tongue in cheek. There are serious ideas on the best list, such as "A Google 'minus' button for each listed result. " so humor isn't a requirement, but funny ideas usually do better in the voting results.
A word of warning about the Half Bakery: You can loose hours of your life, reading and laughing and thinking about the great ideas posted here.