I have a few...
First of all the Portal of Power for Skylanders...
Yes... it does allow me to play the game... but what else does it do? Nope... nothing... it just sits gathering dust, and makes you wonder why they didn't just give you a particular code... or even make it kinect/eyetoy/webcam compatable, and not just a hulking pointless bit of plastic! :/
Next... these guys:
These are pretty much a product of my hoarding... My old PSP broke, and I got a 3DS instead, I got a Blu-ray player when HDDVD died, and my minidisk player hasn't seen a battery since I got my first iPod... but for some reason I kept all of the disks for all of them... well... I dunno why! :S
Also, interesting to see that 2 of them were unsuccessfull Sony ideas! It's impressive that sony come up with most of the info storage and media devices, but only aroung half of them are accepted into common use... the rest fall to the wayside and are hardly used again!