I bought this the other day, turns your phone into a laggy, semi headache inducing Oculus Rift. That said, its fun.
But for a PS10'er its a great secret santa or stocking filler.
Google Cardboard Virtual Reality (VR) Headset with programmed NFC Tag and elasticated head strap: Amazon.co.uk: Electronics
This one is good as it comes with a headstrap.
Some people have also worked out how to hook it up to their favourite games (with a bit more effort) : http://www.reddit.com/r/EliteDangerous/comments/2o5j30/using_google_cardboard_or_equivalent_kit_as_a_vr/