Overall a great plugin. I think the idea to minimize the tag list unless the USER wants to do something is quite good. Moreover, it is very aesthetic. The usage was very straightforward.
However, the styling is quite dodgy, so you'll have to hack the code. For an example, and I do NOT encourage stealing, look at my site or the authors site to see what you can do.
Also, this addon does not provide any back-end options, which is usually always a welcome thing.
It would maybe be cool to show only the letters that indeed have tags attached to them instead of the whole alphabet.
Graceful no-javascript degradation would add to the value.
I think I'm done.