Being a new developer (or a seasoned veteran) you are always learning. At your job you are hopefully learning new things all the time. But there might be projects or tasks where there is not much room for improvement and you are looking to try something completely new. Here are a few sites that can teach you about new areas in the programming world or give you new interesting challenges and maybe make some money from it.
Hacker Rank is a place that acts as a way to improve your skill in multiple areas of programming and get noticed by potential employers. You complete increasing difficult challenges that are ran in real time on their site. You can code most challenges in the language of your choice, unless the challenge is teaching you a specific language. For each challenge you complete you get points. This is a great way to have a friendly competition between your coworkers. The site also has contests that you can participate online to see how you do against other developers in that area. Some contests are also in person challenges where you can win money.
CrowdANALYTIX is a bit different in that you are competing against other developers to have your solution chosen for the given problem. All problems are real scenarios where someone needs a solution. If your solutions gets chosen, you get the prize money. This can be up to a few thousand dollars per problem. The problems are quite large in size and require a lot of work. If you are looking for a bit of a side project this is a great place to get some ideas.
Project Euler is more math based than programming based. You still need to code each problem as you can not simply do the math in your head. Even if you are mainly a developer that focuses on user interfaces or business process. Its still good to look into other domains and expand your way of thinking. These challenges will teach you to make your code more efficient.
Coding Game is a set of games where you need to code the last piece of the game. You usually end up making a simple AI for some character in the game. These challenge start out fairly easy, but ramp up in difficultly very quickly. As you complete games you get points based on how well you did and how efficient your solution was.
All these sites give you the opportunity to learn some new tricks and gives you a different way of thinking for the same issues you come across each day. Hopefully you find some of these challenges and games fun. Bit of a break from the business world we all usually develop in.