A font to make sparklines in seconds
Oops, the site was hackernewsified and is intermittently down for me.Neat idea, and I do like the OTF hacking, but why not use simple SVG?    
      
      <path d='m 0,0 L 10,5 20,8 30,6 40,3 50,-2 60,-8 70,4 80,6'
            fill='none' stroke='black'/>
      
    

It has the advantage of using actual data, it is trivial to generate, is embedded into HTML without an extra fetch, won't confuse screen readers, doesn't require the normal web-font alternative file format dance, and isn't quantised to a set of precreated values.Poor old SVG, it is constantly being reinvented.