An "Internet of Things" starts with temp/motion sensors like these Wireless Sensor Tags from Cao Gadgets
Imagine an "Internet of Things" where even the smallest device could store and report information about itself or whatever it is attache to. These Wireless Sensor Tags are a big step in that direction. These small devices can be attached to doors, windows, mailboxes, keys..almost anything actually…and then report back to you -- via web, smartphone, SMS, etc -- whenever they are moved or whenever temperatures exceed programmed minimums.
For myself, I could see putting one of these in my mailbox so I could tell when the mail had arrived or placing one on the garden gate so I would know when the meter readers (or others) had entered my back yard. You can probably come up with a hundred different uses for these devices and the web site has a host of ideas (and video demonstrations) to get you started.
You can also use the Wireless Sensor Tag to let you know where something is in your home -- like the TV remote, keys or whatever else you have a habit of misplacing. You can use your smartphone or PC to tell the device to start beeping so you can hunt it down.
The Ethernet Tag Manager (which plugs into your network) and 3 tags will set you back about $91 when purchased together.