One of the coolest things you can do with any Android device is play old school games using emulators. My personal favorites are NBA Jam for the Super Nintendo and Mario Kart 64 for the Nintendo 64. Unfortunately, unless you have an Android tablet, playing emulators on your HTC EVO can sometimes be a little awkward.
We've mentioned a few ways to making things a little easier, like a DIY EVOcade, EVO-Tainment gaming system, or using a PS3 controller. However, you need to be rooted and running an AOSP ROM to get any of these solutions to work.
But now there's BT Controller, a nifty little app that doesn't require root and turns one of your Android devices (e.g., EVO 3D) into a gamepad while letting you use another Android device (e.g., EVO View or EVO 4G) as the "screen" to display your games.
The app has been confirmed to work with the most popular emulators available for Android, but your mileage may vary (depending on which games you're trying to play). Have fun!
The paid version of BT Controller is $0.99, which removes the ads that are in the free version linked below.
Links: Market (EVO) | Market (web)
[Addictive Tips]