Don't know if this website has already been mentioned on here before, apologies if so.

http://spendingchallenge.hm-treasury.gov.uk/

Some of the suggestions are utterly hilarious, I can't believe they left it completely unmoderated!

Examples:

Employ Crocodiles in Benefit Offices
http://spendingchallenge.hm-treasury.gov.uk/how-can-we-rethink-public-services-to-deliver-more-for-less/employ-crocodiles-in-benefits-offices

Force cats to spend 1 hour per day on electrical treadmills
http://spendingchallenge.hm-treasury.gov.uk/how-can-we-rethink-public-services-to-deliver-more-for-less/force-cats-to-spend-1-hour-per-day-on-electrical-treadmills

Legalise crack, speed and heroin but not cannabis http://spendingchallenge.hm-treasury.gov.uk/how-can-we-rethink-public-services-to-deliver-more-for-less/legalize-crack-speed-and-heroin-but-not-cannabis

And that's not even mentioning all the hilariously (but slightly terrifyingly) bigoted immigration stuff...

The comments are also great