What follows is a list of MEL-related resources, plus a bunch of other stuff..

Sources for learning more MEL:

While Maya's own Script Editor window is ok for writing interactive MEL, these are better alternatives:

For disk-based scripts, you can also use emacs or vi as your text editor, if you are 'ancient' :) Otherwise, try jEdit, UltraEdit etc.

Here are a couple of "UI builders":

This is "Processing', an amazingly compact, powerful and FUN environment for coding 2D and 3D graphics as well as image and video processing (with audio) apps.You can easily program Processing apps if you know MEL, Python, C, Java, JavaScript etc.

Additional assorted refs:

fundza - Malcolm Kesson's wonderful site (also mentioned above for 'Cutter')

Three great virtues of programming and much more