NASA Podcasts - Informative podcasts in the field of astronomy and earth sciences. Programs are directed to 5-12 but could be used for all grade levels. A full transcript is provided with each podcast. (http://science.nasa.gov/podcast.htm)
NPR Science Friday - Achrived broadcasts from NPR Science Friday hosted by Ira Flatow covering news in science, technology, health and environmental issues. Most appropriate for older students. (http://www.sciencefriday.com/)
The Math Factor - A variety of math topics are discussed by C Goodman-Strauss, professor of mathematics with the Unviersity of Arkansas. The site also has math puzzles, games and a section of math weirdness. (http://mathfactor.uark.edu/)