RF id (Radio Frequency Identification) can be applied to a product for the purpose of identification or tracking using radio waves. Its already a common place technology used extensively in passports, malls (for inventory management)  and toll gates (for toll collection);  and its time it entered our homes too!

For those prone to losing things at home (your car keys for e.g.), here is a technology thats a saviour.

In future homes, here is how it will work. Using a RFid tag gun, you feed in basic attributes, like an identifiable name for the item and tag it. Once tagged, you could use your device (mobile phone or your computer) to keep an inventory of all items in your house. If you’ve misplaced things in your house, all you need to do is search it from your device, and your device will tell you exactly where it  is!

RFId gun - Source FlickR Joebeone

This technology can also be used for theft prevention, for e.g. a sensor can be configured to alert the owner over SMS if an item has been relocated from its original place.

Thesee are examples I could think of, and its applications are varied. The thing about these RFid implementatins,  is that its not too futuristic, and some of the above solutions are on the horizon!