One of the best ways to "spend" money is by investing in your own retirement. When you do this, you're spending the money now, but you'll be receiving it back in the future, plus a ton of interest.
Besides that, spend money on things that either save you money or help you increase your income. Books that teach you new marketable skills or help you hone your abilities are always good. Energy efficient appliances and tools to reduce your expenses at home are great. High quality merchandise that will last a lifetime is more economical than cheap, poorly-made items that have to be replaced frequently.