Not a competition, but I subscribe to Martin's Money Saving Expert weekly email. It is full of ideas to save money, discounts for meals out, info on how to switch utilty companies.
Today I followed a tip to get a free credit rating, which then awarded me £8 on a cashback site. You need to read the guidance carefully as there are terms and conditions.
But £8 towards your next CD bill or whatever else could be enticing?!