One of the things that you can do with these devices is stream media. There are several different devices out there including
- Apple TV
- Roku 2 (XS or HD)
- A variety of Blu-Ray Players
- Gaming Devices like: Xbox 360, Sony Playstation, Nintendo Wii
These devices allow you to connect to a Wi-Fi network and stream a variety of services: The most common are Hulu, Netflix and Pandora. The first two are video resources and the third is Audio. These devices can also sometimes be configured to play media from your computer. These types of devices then can be used to stream media you use in the classroom.
You can see CNET's review of some media players here: http://news.cnet.com/8301-17938_105-20025670-1/which-streaming-media-device-is-right-for-you/