We tend to cover custom ROMs and other mods pretty heavily, but there's an incredibly vibrant theme community around Android. One of its most active participants is Team Carbon, which announced today that its themes for the CyanogenMod (AKA T-Mobile) theme engine have reached a million active users. That's not total downloads, mind you - that's a million people with themes running from three European theme designers. Good on ya, guys!
To celebrate , all their premium paid themes for both CyanogenMod 7 (Gingerbread) and CyanogenMod 9 (Ice Cream Sandwich) are one-third off in the Google Play Store. You can see all their products here. (Not all are CyanogenMod themes.) Keep in mind that CyanogenMod isn't the only ROM that accepts compatible themes - many custom ROM builders, including the AOKP team and various other with modded and "deodexed" builds, use the same standard.
Team Carbon's themes aren't just palette swaps - they bring a new look to the entire interface, from the widgets to the dialer to the individual app icons. But unlike manufacturer skins like TouchWiz and Sense, there's no significant hit to performance, since the themes simple replace system files without adding any new software. Of course, not all themes are compatible with all ROMs, especially those that stray from the official CyanogenMod source. Be sure to try out your theme during the Play Store's 15-minute return window.