No matter what level of math you're teaching, showing your students examples of how they might apply their math skills in the real world is a great way to engage them. Here are five quick examples you can use, but I hope that you use this as an inspiration to start seeking out your own.
Cheaper To Get Four 2-Slice Deals Than A Whole Pie [Consumerist] - I suggest searching for stories about Target on this site as well; that store seems to exist in it's own mathematical universe.
Is This A Macy's Ad, Or A Math Test? [Consumerist]
Laundry Costs Calculator Shows How Much You Spend Washing Clothes [Lifehacker] - Might not be applicable if many of your students don't have washing machines at home (like yours truly), but still interesting to consider.
Teaching Preschoolers About Money: An Interview With Beth Kobliner [Wise Bread] - Includes a video featuring Sesame Street's Elmo and discussion questions to try out with your young children/students.
Garden Math: How Many Tomatoes to Plant? [Wired: Geek Mom]