That's an elegant, simple solution! Quick to set up and use.
I'm using Moodle 1.9.7 and my installation is marginally different, however.
I downloaded and extracted the files.
Instead of copying the extracted file:
into the <moodle installation directory>/lang/en/ folder, it should go into the
<moodle installation directory>/lang/en_utf8/ folder for newer versions of Moodle.
Also, the entire extracted folder
can merely be copied into the
<moodle installation directory>/blocks/ folder.
The quotes.txt file can be edited directly there. Each quote must be on a single line. (The bold tags supplied in the example quotes.txt file are, of course, optional.)
Of course, it is important to add the block module as usual (as a Moodle administrator) using
Moodle -> Site administration -> Navigation (making sure to click on the Navigation menu item so that upgrades occur).
It should then appear as a block module for placement anywhere. Works great!