We have the more expensive Audioengine 5+ speakers on our Best gifts for under $500 for dads list. But we've always had a soft spot for the smaller and more affordable Audioengine 2 speakers, which come in white and black and retail for $199.
The new iPad starts at $499 for the Wi-Fi 16GB model. Ideally, you'd probably want to go with the 32GB model, but hey, if you only want to spend $500, let the kid bring the iPad back to an Apple Store and upgrade it to whatever capacity he or she wants (as long as they pay for it).
The Vita offers a true next-gen gaming experience in the palms of your hands. It's somewhat pricey, but grads won't care too much about that if you're paying for it. Just don't forget to pick up a memory card when you buy it.
Logitech's Wireless Boombox for iPad is a portable -- and affordable -- Bluetooth speaker that also happens to sound good. Though its name implies that it's designed for the iPad, it also works with any Bluetooth-enabled smartphone or tablet.
You can always buy a grad a Sony PS3 to use as a Blu-ray player, but if you want to keep the gaming out of it, a standalone Blu-ray player is always an option. A CNET Editors' Choice, we consider the Panasonic DMP-BDT220 the best value in Blu-ray players today.