Love it! I've entered this into our "Halloween" art challenge.
http://opengameart.org/forumtopic/weekly-challenge-halloween-due-oct-31

The theremin really nails it!

Well done!

I'll probably make the "depleted" version darker so that I can, in my colorblindness, more quickly see the current levels.

I made additional renders of this for a vertical-scrolling shooter
http://opengameart.org/content/spaceship-banking

I'll start!

I'm using very boring health and mana bars in OSARE.  Look at these screenshots: http://clintbellanger.net/rpg/screenshots.php (the green and blue bars on the top left).

The green bar is health.  When it gets halfway down it becomes a red bar.  I'd like to replace that whole thing with a bar that is either all red, or a gradient from red to green (or red to yellow, to follow a more standard convention).  I'd like a grungy, gritty texture on it: something that invokes "bloody" or "natural".

The blue bar is mana.  I still want it blue, but it should invoke "magic" or "ethereal".  One direction might be bands/wisps of color as you'd see in an Aurora Borealis.

Each bar is 100px by 12px.  (I calculate % health or mana and display that many pixels of the bar).

Let me know if you have questions!