I think you guys should have an open market where everyone can make their own themes, and share them with the rest of the community.
I personally also want to completely design my own theme.
If not that, I suggest your designers work on a new theme that includes a full rainbow gradient as an outline to the keys, with black as the main color.
Something of that matter: http://imgur.com/a/BVE01
Thank you so much, I am enjoying your app. I would love to see a theme like that implemented, or even having the option to design your own themes.