Here is an example what it can do,
Basically it is a hello world.
a more practical example is this, it is a rough statistics on internet user in the dorm:
http://chart.apis.google.com/chart?cht=p&chs=200x125&chd=s:Nu&chl=niu|iuniu=non internet user
the catch is you need to encode your data into a string, notice the chd, that is the data encoded.
you can find more info on the links above.
The thing is this is an easy way for us to actually, visualize data for our website. the fact that it uses a rest interface, does make it easy, to write script to automate task