-Speakers
-Camera
-Optical Drive (bring a CD with you)
-Audio ports (bring some headphones)
-USB ports (bring a usb drive with you)
-Mic
-SD card slot (bring an SD with you)
-Check the display for dead pixels, fading, tinting or any other imperfections.
-Make sure wifi card works
-Bluetooth
-Check for any odd noises, like odd clicking from the HDD which could indicate a failing hard drive
These are just a few, you could check a ton of things.