Logitech's Tablet Speaker is one of those products that might not blow you away in any department, but its simple, versatile design and inexpensive price makes it an easy impulse buy, especially for those looking to augment the sound of their iPad for movie viewing.
The speaker--which is fairly lightweight at 6.5 ounces--is 8.5 inches long and clips onto the top of the iPad and larger Android tablets. You then plug the cord into the 3.5mm headphone jack on your device, hit the power button, and you're good to go.
It's worth noting that the clip opens pretty wide so there's some leeway in terms of what you can clip it onto. For example, I clipped it onto an iPad that had a case on without any problem.
However, the one limiting factor to what you clip onto is the length of the cord--it's 13 inches long (it does fold into the speaker and hide away for transport, which is nice). That means you can only clip the speaker onto the top of a small laptop like the 11-inch MacBook Air in order to have the cord reach the headphone jack.