The value of Wikipedia is becoming harder and harder to contest. This particular remix of Wikipedia (5500 articles, 20 volume encyclopaedia, 34 000 images, and 20 million words) should be downloaded by school and burned to dvd for every teacher and student to take home in their pocket.
And while you're at it, for your own professional development read what Wes has to say and download the entire K12 Online Conference (3 years worth of high quality PD) to carry around in your iPod. Take it in on the bus, or any time you have a free moment; maybe over coffee in the staff room. If you have a video iPod you could share it with a few of your colleagues.