Reported by Rob:
Last night I was converting $1.0.$2.1.$3.2.$4.2.$5.0 to x02210 which simplifies things a lot. I noticed however that no matter how many spaces you have between x02210 x02210 it always only renders to one space whereas before I used the spaces to indicate timing. Is this a difficult issue to fix? For now I will just keep to the more extensive notation $1.0 etc...

currently diagrams are drawn in only one size. Add ability to support at least 3 sizes.
Side goal: squeeze 4 bars of tab to a line

Add drawing effects for:
hammer-on
pull-off
bend
release
trill (For trils I use ~~~ but they are not so clear as they are plotted right on the line... could it be say 0.5mm above the line?)

suggestion from Rob Vissers

rendering currently takes ages in IE8 compared to FF or IE7/6 on my machine

Chord diagrams don't render a barre symbol or other common annotations

currently only common, usually open tunings are support in chord notation.

Be nice to be able to:
(a) specify specific variations to render (b) interact with the chord diagram to select/browse variations

Currently only six-string beasts. No bass, lutes, mandolins, banjoes etc etc..