There may well be 50 billion device coming, but the most exciting things in the Internet of Things are the ones you can hack. I've developed a new weekend hobby of connecting and hacking devices. Here are my top 5:
Philips Hue
These connected lights bulbs have an HTTP API that is really easy to use and allows you to control single and groups of lights. You can control the colour range, brights and hue of course. Furthermore your partner will love the pretty colours and you'll convince your kids you can do magic.
Google Glass
Yes this is the device that is paradoxically cool not cool. It has a REST API that gives you access to post items to the Glass timeline and subscribe to location and updates from it. The REST API is pretty limited, but luckily Glass runs Android and has a GDK for writing apps for the device itself, which greatly extends the possibilities.
Raspberry Pi
This $35 linux box is perfect as the hub to connect to other things. You can get modules to tracking location, attach a camera, or any USB device. Most IoT sensors will connect to a hub to get to the internet, and Raspberry Pi is great hackable hub device. Here is me putting an API on it.
My kids love this one, its a ball you can control wirelessly and change its colour. Sphero is a little harder to hack since it only has a bluetooth API (and if you've tried coding bluetooth using Java on OSX 10.9 you'll know that mix of OS, VM and protocol stack doesn't work well right now). But there is an SDK that works well with Node to give you full control over the ball with simple commands.
Smart Things
This is a collection of sensors and devices that can be used to program other things. You can control lights, motion sensors, power sockets, etc. Interestingly Smart Things created their own DSL (based on Groovy) but you can only access it their own web-based IDE. The good news is that you can create web hooks to send device events to other applications, like Mule.
Happy hacking!
