Thingspeak is a very interesting site. It collects (and display) a lot of data from different sensors, contributed (of course) by end users.
It is interesting to see what it is like to connect a just built thermometer using a Spark Core and a TMP36 temperature sensor to Thingspeak. Currently, it is measuring the temperature of my living room.
![Connected thermometer](http://blog.l3l4.com/wp-content/uploads/2014/09/Thermometer-300x224.jpg)
![Room temperature graph](http://blog.l3l4.com/wp-content/uploads/2014/09/TempGraph-300x166.jpg)