One of my all time favorite online simulations is the lemonade stand game. Just about everyone starts thinking about lemonade in the spring. This game lends itself to some easy integration of mathematics and technology. With a little planning, you can create an excel spreadsheet that students can use to track their progress through the game. If you want to know how to do this with your students and get a free copy of the directions for creating the spreadsheet, keep reading.
You can either give students the directions to create their own spreadsheet or give them access to a template you create in advance. The game provides a challenging simulation where students must take into account money spent on supplies, weather factors, and customer satisfaction as they determine exactly how much of each ingredient should be added to get the perfect pitcher of lemonade. To make it more fun, I usually offer free lemonade at lunch for the person who "makes the most money" by the end of the month in the game.
If you want the focus to be on the math, print this template and have students fill in the data by hand. They can either do the math with pencil and paper or use a calculator.