Web/Graphism : how to generate a fake image online ?

You need to generate a fake image of a given size ? A simple way for this is to use the online website http://fakeimg.pl

For example :
http://fakeimg.pl/300/
http://fakeimg.pl/250×100/
http://fakeimg.pl/250×100/ff0000/
http://fakeimg.pl/350×200/ff0000/000
http://fakeimg.pl/350×200/?text=Hello
http://fakeimg.pl/350×200/?text=World&font=lobster