Dare I make a Feature Suggestion?

[DetlevD]

@Patch

... I'm just now looking into adding artwork based on the GENRE tag. ... run an action that would fetch a piece of artwork (from a user defined location) based on the GENRE tag of the track ...

This is already possible with Mp3tag action "Import cover from file".
You have to define and setup a useful textual relation in between Mp3tag and the image file by the filename.
Read something similar there ...
/t/10732/1

@Patch

... add text to the artwork based on the ARTIST and TITLE of the track. The colour of the text could even be automatically altered based on the tags. ...

Putting text onto a picture, that is the task of image processors like Imagick or Irfanview or whatever else specialised batch script driven application.
You have to develop a suitable workflow between Mp3tag and the external image application.
That means to export the text data and the color names for foreground and background colors and the transparency value and other possible arguments for colored frames, font type, font size, image file type and so forth.

DD.20140305.1609.CET