The Audio-Technica ATR3350 is an inexpensive, wired, lavalier microphone with a 3.5mm plug that can be used in many video situations where you need to up the quality of the audio that you are acquiring. A common usage would be to improve the audio when using a DSLR camera for video by plugging this mic into the microphone input.
For about $35, you get the microphone with a lapel clip, battery, and tiny wind screen. The wire is about 25 feet long, giving you flexibility in the distance you can be away from the camera. There is an On/Off switch to activate the microphone, however there is no light indicating that it’s on, nor is there any indicator for the battery level. But for the price, it is certainly better than using a video camera’s built-in microphone.