It has been quite a while since MIUI integrated the Free Desktop feature in its ICS and Jelly Bean ROMs. But we have only three themes available till now. Two out of three, namely the Angry Birds Space and Warmspace have been released by MIUI Resource Group itself. The third one is the WP7 Metro theme made by Kingz Cheung. Besides, we have several modified versions of these themes.
Here is another Free Desktop theme called My Home. It has been designed by a Chinese theme-maker Whbo. The theme is compatible only with HDPI (480p) devices and looks very beautiful. It has been modified a little by me but all credits to the original author.