Storefront has 10+ WordPress eCommerce themes and support WordPress e-Commerce, WooCommerce and Jigoshop plugins.
Tokokoo Provides fully responsive layouts, integration with popular plugins and Facebook pages. 10,000+ stores run on Tokokoo themes.
WooCommerce – Though WooThemes made other niche themes in the beginning, its new focus seems to be on producing Business themes with WooCommerce support. They have tens of premium eCommerce themes and guess what: Check out their free themes too.
SplashingPixels seems like a new player in the arena. They have couple of good looking themes and support WPEC and WooCommerce.
Do you know more shops that exclusively design WordPress eCommerce themes? Please let us know in the comments.