New day, new app in Cydia store: IconHarvester. IconHarvester lets you download iPhone and iPod Touch themes and customize them to suit your tastes. Once you are find a theme that you like and you customized it, the app uses Winterboard to apply the theme to your device.
When you launch the app, you will find a huge list of available iPhone themes. Tapping on any theme will get you a preview of that theme and you can choose to install it on your iDevice. Once the download is complete you can choose to set icons for each app on your iDevice.
Once you are done with all the customizing, exit IconHarvester and load Winterboard. To activate the customized theme, you will need to select the normal theme , as well as the customized theme. Exit Winterboard and wait for your iDevice to respring. That is it, enjoy your new customized theme.
You can find IconHarvester in Cydia Store for $4.99