I'm sure you've seen one or two of those Android watches that looks so gimmicky and you don't really know what you want to do with it, plus it can be expensive. Ars Technica somehow was able to run real Android apps on Samsung Galaxy Gear!
This of course need some technical know-how. You need ADB on your computer and you need to set up the phone for USB debug. You would also need the APK file of the app you want to run which you'd have to sideload into the device. More info on how it's done here
Here's the Samsung Galaxy Gear at work, making use of the usual Android app.