While this is nothing particularly surprising and local location solutions have been using RFID for years, I don't think we mentioned before such a simple solution using Bluetooth. In a Kickstarter-like crowdfunding launch, here's the StickNFind- Bluetooth Powered ultra small Location Stickers.
From CNET: "StickNFind stickers are equipped with Bluetooth low-energy technology. The stickers are about the size of a quarter and weigh well under an ounce. Slap a sticker on anything (or anyone) and then use the accompanying app to figure out where you put them last. Each little tag also has sound and light that can be triggered separately. The StickNFind app can be set to work kind of like a radar or it can send you an alert when an item comes into range. You can also get a warning when an item (like Sir Fluffypants) goes out of range."
Before you ask, from the officlal FAQ: "Range: Approximate 100 Feet with line of sight. Battery: Lasts up-to 1 year based on 30 minutes per day average use."