Based upon http://freestyler.ws/style/101158/tweetdeck-snowflake-classic-black and features of http://pixelde.su's Modern TweetDeck, plus a bit of my own, here comes Snowflake Minima Black.
Yes, the thing is damned buggy, but we're working on it.
Also, the code is pretty messy, since it's a fork of another project and a bit of my own messy and rusty CSS skills.
Please note that the screenshot was taken with Better TweetDeck Chrome extension applied, and the rounded avatars or textless buttons on the compose panel aren't part of the default theme. I can implement rounded avatars if you want to, though.
Also, you need to use it with Dark TweetDeck.

Had to remove the custom font, but you can get it on our https://github.com/WinterReign/Snowflake/.
This is part of the https://github.com/WinterReign/Snowflake/ suite.