Enter IP Webcam, an application that allows you to use your EVO, EVO 3D, or other Android device as a wireless standalone IP webcam.
You will have to download and configure a driver from the author's site if you want to use your phone as a connected webcam on your PC, but by itself IP Webcam contains a video streaming server that you can connect to via browser or media player.
So, if you're looking for something to do with an old EVO or Android device, or you just need a wireless webcam to spy on cats or a baby, IP Webcam is a useful little free program to play with. Do keep in mind you are most likely subject to governing laws concerning hidden cameras, so please don't use this where you're not supposed to.
Links: Market (EVO) | Market (web)