I have found many useful resources on line. Some I use as a resource for ideas of activities, and others are activities within themselves. In math, we use McDougal/Littel text. They have a resource for activities called classzone. It is loaded with power points that go through the examples in the book, and also animated games that help the students understand the concepts. I use the activities with a Smartboard. Another resource for activities that can be used with Smartboard is a website called shodor.
One resource I use just for ideas for activities that I can create is education.com. I have found this to be a source of many great ideas for games and activities to do with the kids. Some of the games are geared for a younger audience, but with slight modifications, they can usually be altered to work for my class.