> Not sure if this is 100% "correct", as I suspect it is a "bending" of
> the spec, but have you considered Ruby? http://www.w3.org/TR/ruby/ 

That's quite cool. I played with it a bit more:

<style>
   p { ruby-align:left; }
   rt { font-size: 75%; }
</style>
<p>
   Bla
   <ruby><rb>bla</rb><rt>A</rt></ruby>
   <ruby><rb>bla bla.</rb><rt>E</rt></ruby>
</p>
<p>
   Bla
   <ruby><rb>bla</rb><rt>Am G F E</rt></ruby>
   <ruby><rb>bla bla.</rb><rt>Dm</rt></ruby>
</p>

This workes really well.

You need ruby-align: left, because the chords starts at the beginning of 
the word. Unfortunately, this also makes the fallback feature of ruby 
useless, because <rt> has to follow <rb>, so the chords always end up 
after the words. I think the order restriction is unnecessary, maybe 
this can be fixed in a next version. (But Internet Explorer would have 
to be fixed as well then.)

-- 
Sjoerd Visscher
http://w3future.com/weblog/