Android has been evolving for the last several years and expanding its reach through various phones and tablets. At Google I/O 2014, they announced that they are standardizing the Android landscape across phones, tablets, in addition to wearable technology such as Glass and Wear, TV and even cars! All of these devices run the Android OS and give you many avenues to create innovative new systems.
One of the latest additions to the unified platform is Android in watch form.
This exciting new platform not only provides notifications (similar to the status bar on your phone), but also provides new modes of interaction. If you have an existing application with notifications, you already have a presence on Wear.
If you're interested in Wear, check out Android's website: http://developer.android.com/training/building-wearables.html
Google Glass is a notification engine, camera, video recorder, and application host on your face. Controversy aside, there are plenty of interesting technical aspects to explore.
There are two basic flavors of Glass apps. First you can write applications with the mirror API, which delivers content to your Glass using your own backend. You deliver HTML-based cards for display.
The other option is to write native Android applications using the Glass Development Kit (GDK). If you're interested in developing Glass apps, check out the developer website: https://developers.google.com/glass/develop/gdk/
Google's latest attempt at putting Android on your TV was announced at Google I/O this year. Instead of running a fork of Android, as the ill-fated Google TV did, it now runs full, native Android. It also has casting abilities builtin (integrated Chromecast).
If you're interested in developing TV apps, here's more info: http://developer.android.com/preview/tv/start/index.html
We know relatively little about the platform since it was recently announced, but it'll work as a second display and an input device. Your apps will run on the integrated Android device in the dashboard (not on the car).