
If any one of the people walking around the rim of this glass was paying attention and not chatting on their cell phone, they may realize that when this glass is being used they are all upside down. And any time you open a cupboard to get one of these glasses out you can see that even in the darkness of the cabinet they continue to talk. Get a whole set of these glasses and your cupboard will look like it is hosting a tech fair.
Product Page (£19.95, about $32)

It may take your guests a little while to figure it out, but that new painting in your house that they enjoy so much also happens to be a cell phone jammer. Nothing is more annoying than a visitor to your house spending all their time on the phone, now they won’t be able to make or receive any calls while at your house while you just play dumb. The jammer will block the following frequencies that should cover all cell signals: CDMA: 870-880MHz; GSM930-960MHz; DCS: 1805-1850MHz; PHS: 1895-1918MHz; 3G: 2010-2145MHz.
Product Page ($185)

Uh, last time I checked most cellphones had a calculator built-in. So, you know…wtf. It does have a mirror though—so it is not completely useless.
Product Page ($1.15)