Math Central is a lovely website maintained by the University of Regina for both students and teachers. The site offers a resource room, a data base of answers to questions, information on mathematicians, math beyond school, problem of the month and several other sections such as links and outreach activities which are oriented for Canada.
The resource room has a variety of materials for elementary, middle school and high school. Since I teach high school, I checked out some of the high school topics. If you look at all the high school strands, there are 102 activities to choose from. Some topics are a bit esoteric for what is normally taught but they can be used to show students things outside the normal material covered.
The quandaries and queries section holds answers to questions asked by people. The topics are arranged in alphabetical order and each topic might have more than one question and answer associated with it.
The math beyond school has two pages worth of how math is used in real life for grades 10 to 12. The real life examples are available for grades K to 12. While the examples do not include the actual mathematics, they do give a good summary of the math. For instance, the article on airlines provides information on all the different ways airlines use linear programming to help schedule pilots, sell seats, and keep costs as low as possible.
The final section that is usable is the problem of the month. Although these problems are no longer being produced, the old ones are available to use.