I'd like to suggest Mystile, a free theme by WooThemes as a new theme for the WordPress.com repository. Mystile was originally designed as WooCommerce theme but can easily be used without the WooCommerce features (for example, the shop page and products on the landing page).
The reason I'd like to get Mystile on WordPress.com is because the blog is gorgeous, as you can see on the demo: http://demo2.woothemes.com/?name=mystile
The theme also offers a number of colour options which is fantastic. It's always a pleasure to have a bit of customisation in a theme.
The standard fonts (header, body text etc.) are really attractive. They're clear and easily readable and the layout of the blog is so easy on the eye.
The featured post images are a good size-a plus for an image-rich blog.
The calendar-style date stamp is fun.
Most of all, the first time I saw the Mystile blog page I was hooked. Even more so when I clicked on the "more styles" tab and tried it in the blue and the green. I knew immediately that I wanted to use it on a blog and that it would be a magnificent addition to the WP.com theme collection. It's so beautiful.
WooThemes has contributed numerous themes, free and premium, to WP.com, so hopefully they'd be open to making this one available too.
More info on Mystile here: http://www.woothemes.com/products/mystile/
The blog I need help with is mediajo.wordpress.com.